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Antigone canadensis

• INTRODUCTORY
• DISTRIBUTION AND OCCURRENCE
• BIOLOGICAL DATA AND HABITAT REQUIREMENTS
• FIRE EFFECTS AND MANAGEMENT
• APPENDIX: FIRE REGIME TABLE
• REFERENCES

INTRODUCTORY

AUTHORSHIP AND CITATION FEIS ABBREVIATION COMMON NAMES TAXONOMY SYNONYMS ORDER CLASS FEDERAL LEGAL STATUS OTHER STATUS
	Photo courtesy of US Fish and Wildlife Service

AUTHORSHIP AND CITATION:
Stone, Katharine R. 2009. Antigone canadensis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: www.fs.usda.gov/database/feis/animals/bird/anca/all.html [ ].

Revisions:
On 26 November 2018, the scientific name of this species was changed in FEIS
from: Grus canadensis
to: Antigone canadensis.

Antigone canadensis canadensis (Linnaeus), lesser sandhill crane
Antigone canadensis nesiotes (Bangs and Zappey), Cuban sandhill crane
Antigone canadensis pratensis (Meyer), Florida sandhill crane
Antigone canadensis pulla (Aldrich), Mississippi sandhill crane
Antigone canadensis rowani (Walkinshaw), Canadian sandhill crane
Antigone canadensis tabida (Peters), greater sandhill crane

Throughout this review, subspecies are referred to by the common names used above. The term "midcontinental population" refers to the aggregation of Canadian, greater, and lesser sandhill cranes occurring at spring staging areas in the Platte River Valley of Nebraska (review by [102]).

Size, head profile, coloration [78,158], and geographic range [158] are used to distinguish subspecies. There is disagreement over the validity of the Canadian subspecies; it is intermediate in size and coloration between the lesser and greater sandhill cranes [78] and overlaps both in distribution. It has been suggested that midcontinental populations may interbreed, though this topic needs further study (review by [124]).

DISTRIBUTION AND OCCURRENCE

• GENERAL DISTRIBUTION
• PLANT COMMUNITIES

The distribution of each sandhill crane subspecies is described below:
Canadian sandhill crane: The range of the Canadian sandhill crane is difficult to define because of its potential interbreeding with lesser and greater sandhill cranes. It is thought that Canadian sandhill cranes breed across subarctic Canada, from northern Ontario through northern Alberta, Saskatchewan, and Manitoba to west-central British Columbia. Birds from the eastern portion of this range winter mainly in coastal Texas with greater sandhill cranes. It is not clear where western populations winter, though it is likely that they winter in California, New Mexico, Texas, and Mexico with the western populations of greater and lesser sandhill cranes. In spring, Canadian sandhill cranes stage along the Platte and North Platte Rivers in Nebraska (review by [102]).

Cuban sandhill crane: The Cuban sandhill crane is found only on the island of Cuba and the nearby islands and keys of the Cuban archipelago ([158], review by [102]).

Florida sandhill crane: The Florida sandhill crane occurs in peninsular Florida from the Everglades north to southern Georgia in and around the Okefenokee Swamp ([113,158], review by [102]). It is thought that its range once extended throughout the southern United States. As of 1996, the greatest abundance of Florida sandhill cranes occurred near Florida's Kissimmee and Desoto Prairies (review by [102]).

Greater sandhill crane: The greater sandhill crane nests in the northern United States and southern Canada, from the Great Lakes west to the Pacific Ocean [158]. Five populations of greater sandhill cranes are discussed here, though there may be additional geographically and morphologically distinct populations.

Eastern population: The eastern, or Great Lakes, population of greater sandhill cranes breeds in south-central Canada and the north-central United States in the Great Lakes area, including southern Ontario, Michigan, Wisconsin, northern Illinois, northern Iowa, and southeastern Minnesota (review by [102]). Individuals observed in Maine may belong to this population [104]. The eastern population migrates through the east-central United States to wintering grounds in southern Georgia and central Florida. Birds from the western part of the breeding range may winter along the Texas Gulf Coast (review by [102]). The primary staging area for the eastern population of greater sandhill cranes is the Jasper-Pulaski Fish and Wildlife Area in northwestern Indiana [89].

Prairie population: The prairie population of greater sandhill cranes breeds in northwestern Minnesota, southwestern Ontario, and southern Manitoba. They winter along the eastern Texas coast of the Gulf of Mexico west of Houston (review by [102]).

Rocky Mountain population: The Rocky Mountain population of greater sandhill cranes breeds in west-central and southwestern Montana, central and eastern Idaho, northeastern Utah, western Wyoming, and northwestern Colorado. Colorado's San Luis Valley is a major spring and fall staging area for this population. Its main wintering grounds are in the Middle Rio Grande Valley in New Mexico [31,158], with other scattered wintering areas in southwestern New Mexico, southeastern Arizona, and north-central Mexico (review by [102]).

Colorado River Valley population: The Colorado River Valley population of the greater sandhill crane breeds in northeastern Nevada and southwestern Idaho, migrates through Nevada, and winters along the lower Colorado River in Arizona, in California's Imperial Valley, and along the Gila River in southwestern Arizona (review by [102]).

Central Valley population: The Central Valley population of the greater sandhill crane breeds in south-central and southeastern Oregon and northeastern California, with scattered breeding areas in southern British Columbia and on Vancouver Island. This population winters in the Central and Imperial Valleys of California (review by [102]).

Lesser sandhill crane: The lesser sandhill crane breeds in the Arctic, including extreme northeastern Siberia, much of western Alaska and northern Canada, many Arctic Islands, and potentially the Hudson Bay watersheds of western and northern Ontario. It winters from southern California, eastern New Mexico, western Texas, and southeastern Texas, south into Mexico to Jalisco, Guanajuato, San Luis Potosi, Baja California, and northwestern Sonora. There are a few records of lesser sandhill cranes wintering in Japan with flocks of other crane species [158]. The major spring staging area for this subspecies is along the Platte and North Platte Rivers in Nebraska (review by [102]).

Mississippi sandhill crane: The Mississippi sandhill crane is found only in Jackson County, Mississippi [151,158], though that population may be a remnant of a larger population that once extended from western Louisiana to Georgia and into peninsular Florida [151].

Migratory subspecies: This section is organized by plant communities used in the breeding season or used while staging, migrating, or wintering.

Plant communities used by migratory subspecies in the breeding season:
Canadian sandhill crane: There is little information available on plant communities used by Canadian sandhill cranes during the breeding season. Reviews state that Canadian sandhill cranes occur in boreal forests, aspen parklands [124], muskeg and other shallow wetland communities, open and forested bogs, and other boreal forest wetland types [102].

Greater sandhill crane:
Eastern population: In Maine, sandhill cranes were observed in areas dominated by sphagnum moss (Sphagnum spp.) in mounds <10 feet (3 m) high, American woollyfruit sedge (Carex lasiocarpa), and scattered leatherleaf (Chamaedaphne calyculata). Other common herbaceous plants included sheathed cottonsedge (Eriophorum vaginatum), white beaksedge (Rhynchospora alba), cattail (Typha spp.), threeway sedge (Dulichium arundinaceum), Northwest Territory sedge (C. utriculata), boreal bog sedge (C. magellanica), buckbean (Menyanthes trifoliata), cranberry (Vaccinium macrocarpon), pitcher-plant (Sarracenia purpurea), and spoonleaf sundew (Drosera intermedia). Common shrubs included sweetgale (Myrica gale) and speckled alder [104].

In northern Michigan, greater sandhill cranes occurred in bogs, where common plants included bog Labrador tea (Ledum groenlandicum), leatherleaf, bog laurel (Kalmia polifolia), bog rosemary (Andromeda glaucophylla), trailing arbutus (Epigaea repens) and wintergreen (Gaultheria procumbens), with neighboring trees of tamarack (Larix laricina), black spruce (Picea mariana), red pine (P. resinosa), jack pine (P. banksiana), and eastern white pine (Pinus strobus) [158]. At the Seney National Wildlife Refuge, Upper Peninsula, Michigan, sandhill cranes occurred in an area that was 54% marsh, grassland, and shrub, 7% lowland conifer, 7% open water, and 2% lowland hardwood forest. Predominant vegetation in marshes and along pool edges was broadleaf cattail (Typha latifolia), sedges (Carex spp.), hardstem bulrush (Schoenoplectus acutus), soft-stem bulrush (S. tabernaemontani), and speckled alder (Alnus incana subsp. rugosa) [100], with emergents covering 43% of the wetlands. Lowland conifer habitat consisted of black spruce bogs with an understory of ericaceous shrubs and sphagnum. Bog forests containing tamarack, black spruce, and red maple (Acer rubrum) were interspersed with patches of sedge marsh and strips of upland sand ridges supporting eastern white, red, and jack pines [8]. Lowland hardwood forests consisted primarily of quaking aspen (Populus tremuloides) and paper birch (Betula papyrifera) [100]. In southern Michigan, greater sandhill cranes occurred on irregular, marshy "arms" extending between wooded ridges, tamarack peninsulas, and ash-maple (Fraxinus spp.-Acer spp.) bottomland [155]. Also in Michigan, sandhill cranes occurred in a mosaic of cattail- and sedge-dominated marshes, forested wetlands containing tamarack and various shrubs, and upland forests dominated by second-growth oaks (Quercus spp.) and hickories [53].

In central Wisconsin, greater sandhill cranes occurred in floating sedge bogs, shallow grass, sedge and cattail marshes, and flooded aspen flats. The area was a mixture of low marsh basins and slightly higher sand islands divided by numerous drainage ditches. Basins once held timbered swamps, bogs, and open marshes, while islands once held stands of eastern white and red pine. Repeated fires following artificial drainage consumed most of the peat and forest duff in sandy uplands. Aspen (Populus spp.) and willow (Salix spp.) established on most of the peat, while jack pines and scrub oaks replaced the eastern white and red pines, though some large peat areas remained. Some tamarack-black spruce swamps and leatherleaf-bog Labrador tea bogs persisted; both are associated with grass marshes and vast tracts of even-aged aspen [45]. Greater sandhill cranes were observed on the forested floodplain of the Upper Mississippi River on the borders of Minnesota, Wisconsin, and Iowa. The forest community was dominated by silver maple (Acer saccharinum), elm (Ulmus spp.), green ash (F. pennsylvanica), swamp white oak (Q. bicolor), eastern cottonwood (P. deltoides), hackberry (Celtis occidentalis), and river birch (B. nigra) [68].

Rocky Mountain population: In northwestern Colorado, greater sandhill cranes occurred in open parkland, with sagebrush (Artemisia spp.) -covered ridges interspersed with willow-lined drainages. Open parkland was surrounded by quaking aspen mixed with lodgepole pine (P. contorta), fir (Abies sp.), and blue spruce (P. pungens) at higher elevations [15]. In northern Utah and southwestern Wyoming, greater sandhill cranes used a landscape that included pastures (55%), small grain fields (19%), riparian areas (8%), alfalfa (Medicago sativa) fields (6%), corn (Zea sp.) fields (3%), and other plant communities (9%) [97,98]. In southeastern Idaho, sandhill cranes occurred in a 22,000 acre (8,900 ha) marsh; approximately 80% to 90% of the marsh was covered with emergent vegetation, mainly hardstem bulrush and lesser amounts of broadleaf cattail [31]. In eastern Idaho, breeding habitat included bulrush-Baltic rush-spikerush (Scirpus spp.-Juncus balticus-Eleocharis sp.) and sedge bands surrounding shallow wetlands, beaver-induced wetland ponds along spring creeks, dense cattail bands along a river drainage, mixed willow/sedge bands along riparian corridors, and open sedge/rush basins. Foraging sites adjacent to nesting areas were primarily composed of sagebrush, cinquefoil (Potentilla spp.), rabbitbrush (Ericameria bloomeri), bunch grasses, upland forbs, quaking aspen, and cottonwoods (Populus spp.) [101].

Central Valley population: In south-central Washington, greater sandhill cranes occurred in wet meadows with willows, sedges, tufted hairgrass (Deschampsia cespitosa), and timber oatgrass (Danthonia intermedia). Wet meadow stringers occurred between forested stands of lodgepole pine, Douglas-fir (Pseudotsuga menziesii), grand fir (A. grandis), ponderosa pine (P. ponderosa), and western larch (L. occidentalis) [77]. At the Malheur National Wildlife Refuge in southeastern Oregon, most breeding occurred in marsh vegetation [64,65]. Coarse emergent vegetation in this area included hardstem bulrush, broadleaf cattail, and broadfruit bur-reed (Sparganium eurycarpum) [83]. In eastern Oregon, greater sandhill crane breeding habitat included 6 wetland complexes adjacent to big sagebrush (A. tridentata) or ponderosa pine habitats [84]. In northeastern California, greater sandhill crane breeding habitat included open wet meadows containing rushes (Juncus spp.), spikerush (Eleocharis spp.), broadfruit bur-reed, grasses, sedges, hardstem bulrush, and broadleaf cattail [82].

Lesser sandhill crane: Lesser sandhill cranes breed in arctic tundra plant communities ([16,70,91,119,158], review by [124]). In the Northwest Territories, lesser sandhill cranes occurred on eskers with 75% lichen cover, primarily bryocaulon lichen (Bryocaulon divergens), and other lichens (Flavocetraria nivalis, F. cucullata). Black crowberry (Empetrum nigrum), bog blueberry (Vaccinium uliginosum), and lingonberry (V. vitis-idaea) were also present [91].

In Alaska, lesser sandhill cranes bred in tundra broken up by major rivers, small ponds, and large lakes. Common vegetation included alders (Alnus spp.), short sedges, grasses, moss, bog Labrador tea, dwarf birch (Betula nana), black crowberry, salmonberry (Rubus spectabilis), blueberry (Vaccinium spp.), lingonberry, and dense patches of cotton sedge (Eriophorum sp.). Sandhill cranes also occurred in muskeg with clumps of spruce (Picea spp.) or marshes dominated by sedges and grasses and shallow water. On southern Banks Island, sandhill cranes were found on sand dunes with scattered dune grass [158]. In northwestern Alaska, lesser sandhill cranes bred in the Kobuk River drainage and Kobuk Dunes [103], a transitional area between forest and tundra. The dunes were dominated by balsam poplar (Populus balsamifera), while river valleys were dominated by paper birch, white spruce (Picea glauca), and black spruce forests [119]. On the Yukon-Kuskokwim Delta, Alaska, lesser sandhill cranes bred in an area comprised of heath-marsh tundra mosaics and sedge-grass meadows interspersed with thousands of small ponds [16].

In eastern Siberia lesser sandhill crane breeding habitat consisted of moderately-wet polygonal tundra comprised of hummock mounds surrounded by scattered water. Mosses covered the ground in most areas, forming a 4 to 12 inch (10-30 cm) layer of peat. Other characteristic plants included sedges, cottongrasses (Eriophorum sp.), bluegrasses (Poa spp.), and dwarf willow [159].

Unidentified subspecies (Canadian, greater, or lesser): In the Interlake region of central Manitoba, sandhill cranes occurred in a mosaic of low forested ridges interspersed with low-lying, poorly drained forested muskegs of black spruce and tamarack, open bog and fen muskegs, and small intermittent lakes. Quaking aspen was prevalent in some areas. Elsewhere the forest vegetation was dominated by black and white spruce mixed with poplar (Populus spp.) and paper birch, with jack pine occurring on sandy, well-drained ridges. Muskeg vegetation characteristic of low, poorly drained areas included black spruce, tamarack, sphagnum moss, dwarf birch, ericaceous shrubs, and a variety of sedges, grasses, and rushes. Dominant vegetation of fens included sedges, grasses, bulrushes, broadleaf cattail, willows, and dwarf birch, with scattered black spruce and tamarack. There were limited cereal and hay fields in the vicinity [105].

Plant communities used by migratory subspecies during staging, migrating, and wintering:
Staging: This section is organized into plant community descriptions of 3 major staging areas: the Jasper-Pulaski Fish and Wildlife Area in northwestern Indiana, the Platte River Valley in Nebraska, and the Copper River Delta in Alaska.

Jasper-Pulaski Fish and Wildlife Area: Plant communities around sandhill crane staging areas include a combination of low sand ridges once dominated by black oak forests and prairie marsh grasses, and upland areas with oak-hickory (Carya spp.) forests. Agricultural lands cover a large proportion of the area [88]. The plant communities of seasonally flooded basins and inland fresh meadows vary by location, with some sites dominated by fall panicgrass (Panicum dichotomiflorum), common cocklebur (Xanthium strumarium), marigolds (Bidens spp.), and/or rice cutgrass (Leersia oryzoides). American woollyfruit sedge and bluejoint reedgrass (Calamagrostis canadensis) occur in peripheral areas. Willow and river birch establish on the edges of these wetlands. Inland fresh marshes with wide borders of inland fresh meadow contain marsh grasses and sedges extending from shore, with dense yellow pond-lily (Nuphar lutea), American white waterlily (Nymphaea odorata), and coon's tail (Ceratophyllum demersum) occurring in deeper water. Some areas are dominated by spikerush, American woollyfruit sedge, rice cutgrass, woolgrass (Scirpus cyperinus), or bluejoint reedgrass. Willow, silky dogwood (Cornus amomum), and swamp rose (Rosa palustris) often form dense stands at forest borders. Inland fresh marshes bordered by forests contain dense thickets of common buttonbush (Cephalanthus occidentalis), common winterberry (Ilex verticillata), and swamp smartweed (Polygonum hydropiperoides) at the waterline surrounded by pin oak (Q. palustris), river birch, and willow [88].

Platte River: The vegetation of the Platte River Valley includes riparian woodlands, low shrub islands, mudflats along the river channel, and wet meadow grasslands on adjacent river terraces. Riparian woodland consists of open-canopy, widely spaced eastern cottonwood forest with understory species such as eastern redcedar (Juniperus virginiana) and roughleaf dogwood (Cornus drummondii) [26,115]. In some areas, green ash, hackberry, and American elm (U. americana) are common [26]. Low shrub islands contain yellow willow (S. lutea), peachleaf willow (S. amygdaloides), narrowleaf willow (S. exigua), and desert false indigo (Amorpha fruticosa) [26,115]. Temporarily flooded mudflats are dominated by tufted lovegrass (Eragrostis pectinacea), nutsedges (Cyperus spp.), and common cocklebur. Wet meadow grasslands contain Olney threesquare (Scirpus americanus), sedges, and common spikerush (Eleocharis palustris) [26]. Unvegetated sandbars are also present [26,115]. Agricultural lands are abundant in the area [69].

Copper River Delta, Alaska: Lesser sandhill cranes stage along the eastern Copper River Delta, Alaska, an island of open marsh habitat within the western hemlock-Sitka spruce (Tsuga heterophylla-Picea sitchensis) coastal rainforest ecoregion. The 4 major habitat types are medium shrub, wet meadow, salt grass meadow, and intertidal mudflats. Medium shrub habitat consists of dense stands of sweetgale, Lyngbye's sedge (Carex lyngbyei), purple marshlocks (Comarum palustre), and bluejoint (Calamagrostis canadensis), often in standing water ≤1.6 feet (0.5 m). Stringers of Sitka alder (Alnus viridis subsp. sinuata) and Sitka spruce occur along the numerous streambanks and lake margins. Wet meadow habitat occurs on former intertidal salt marsh areas and consists of a mosaic of plant communities ranging from small ponds and wet depressions to higher, well-drained slough banks. The area is dominated by mosses and also contains areas of Sitka spruce, sweetgale, Sitka alder, and willow scrub. Salt grass meadow occurs on former intertidal mudflats, with Ramenk's sedge (Carex ramenskii), goose tongue (Plantago maritima), Pacific silverweed (Argentina egedii), and alkaligrass (Puccinellia spp.) at the mean high tide line. Moss cover dominates higher tide areas. Woody vegetation is absent, and substrates consist of bare mud and silt. The intertidal mudflat habitat is unvegetated except for a sparse growth of macroalgae (Ulva sp.) [51].

Migrating: Sandhill cranes are an uncommon migrant through bunchgrass (Agropyron spp. or Festuca spp.) and sagebrush habitat in Washington and Oregon [122]. In Colorado, a greater sandhill crane migration stopover site is centered on the Monte Vista National Wildlife Refuge, a large complex of marsh habitat surrounded by many small grain fields [148].

Wintering: In the Okefenokee Swamp, Georgia, greater sandhill cranes wintered in a deep peat swamp-marsh complex, consisting of a mosaic of freshwater wetland types, including emergent marshes, shrub swamps, swamp forests, and lakes [13]. Three major marsh types in the area included macrophyte marshes dominated by American white waterlily, goldenclub (Orontium aquaticum), and flattened pipewort (Eriocaulon compressum), herbaceous marshes dominated by emergent graminoids, including maidencane, broomsedge bluestem (Andropogon virginicus), and sedge, and mixed scrub-shrub marsh with stands of loblolly bay, pondcypress (Taxodium distichum var. imbricarium), fetterbush lyonia (Lyonia lucida), and swamp titi (Cyrilla racemiflora) [14].

In western Texas, lesser sandhill cranes used a variety of habitats in winter, including mixed-grass, shortgrass, and tallgrass prairies. The most abundant grasses included buffalo grass (Buchloe dactyloides), blue grama (Bouteloua gracilis), sideoats grama (B. curtipendula), black grama (B. eriopoda), little bluestem (Schizachyrium scoparium), western wheatgrass (Pascopyrum smithii), Indiangrass (Sorghastrum sp.), and switchgrass (Panicum sp.) [158]. Also in western Texas, midcontinental populations of sandhill cranes wintered on shortgrass prairie invaded by mesquite (Prosopis sp.) and yucca (Yucca sp.), with sorghum and cotton fields nearby [61].

At the Bosque del Apache National Wildlife Refuge, New Mexico, sandhill cranes wintered in wetlands with yellow nutsedge (Cyperus esculentus), bearded sprangletop (Leptochloa fusca ssp. facicularus), barnyard grass (Echinochloa crus-galli), yellow foxtail (Setaria pumila), cupgrass (Eriochloa spp.), Johnson grass (Sorghum halepense), and fall panicgrass [141].

In the northern Central Valley of California, wintering sandhill cranes occurred in riparian forests dominated by Fremont cottonwood (Populus fremontii), California sycamore (P. racemosa), northern California walnut (Juglans hindsii), willows, and boxelder (Acer negundo) [54]. Canadian, lesser, and greater sandhill cranes also wintered in the Central Valley in areas where remnants of valley oak (Q. lobata) woodlands, grasslands, and wetlands were interspersed with large areas of agricultural production. Flooded rice (Oryza sativa) lands, pastures, and areas of native and managed marshes were used by sandhill cranes [117].

Some sandhill cranes wintered in the western grasslands of Washington and Oregon. Grasslands were dominated by Roemer's fescue (Festuca idahoensis ssp. roemeria), red fescue (F. rubra), and California oatgrass (Danthonia californica). Some savanna areas had these grasses plus some cover of Oregon white oak (Q. garryanna), ponderosa pine, or Douglas-fir [66].

Nonmigratory subspecies: This section describes plant communities used by the 3 nonmigratory subspecies of the sandhill crane: Cuban, Florida, and Mississippi.

Cuban sandhill crane: Cuban sandhill cranes inhabit dry savannas and pine flats year-round ([42,156], review by [124]). Overstory trees include tropical pine (Pinus tropicalis), Caribbean pine (P. caribaea), Everglades palm (Acoelorraphe wrightii), as well as scattered shrubs [158] such as trumpet tree (Tabebuia lepidophylla) [156].

Florida sandhill crane: Florida sandhill cranes inhabit a mixture of wetland [14,35,113,144,158] and open forest [35,78,113,158] plant communities. Florida sandhill cranes also use open pastures [35,113,158] and agricultural fields [76,113].

In north-central Florida, Florida sandhill cranes were found in persistent and nonpersistent wetlands dominated by maidencane (Panicum hemitomon), pickerelweed (Pontederia cordata), and smartweeds (Polygonum spp.). In areas with deeper water, yellow pond-lily and American white waterlily were the predominant vegetation. Open pasture zones contained Bermuda grass (Cynodon dactylon), bahiagrass (Paspalum notatum), and common carpetgrass (Axonopus fissifolius). Upland sites contained live oak (Q. virginiana), turkey oak (Q. laevis), and longleaf pine (P. palustris), with red maple and sweetgum (Liquidambar styraciflua) on the lower, wetter sites. Slash pine (P. elliottii) plantations and fields of corn, peanuts, and hay were also present [113]. Florida sandhill cranes were also found in wide-open prairies that contained stands of cabbage palmetto (Sabal palmetto), either lone or scattered trees intermixed with saw-palmetto (Serenoa repens), and occasional longleaf pine or slash pine. In some areas, stands of live oak, or rarely water oak (Q. nigra), occurred. In lowland regions, redbay (Persea borbonia), sweetgum, baldcypress (Taxodium distichum var. distichum), and red maple were present [158].

In the Green Swamp of Florida, Florida sandhill cranes occurred in a mosaic of pondcypress and swamp with loblolly bay (Gordonia lasianthus), sweetbay (Magnolia virginiana) [35,158], and swamp bay (Persea palustris); herbaceous marsh; longleaf and slash pine flatwoods; scrub oak (Quercus spp.); orange groves; and bahiagrass pasture containing scattered oak and pine [35].

At the Loxahatchee National Wildlife Refuge, Florida, Florida sandhill cranes occurred in wet prairie communities of relatively low stature plants interspersed with stands of sawgrass (Cladium sp.). The dominant plants of the wet prairie community included Tracy's beaksedge (Rhynchospora tracyi) and slim spikerush (Eleocharis elongata). Also present were slough aquatic communities which supported American white waterlily. The wetland complex was broken up by thousands of tree islands varying from a few trees to several hundred acres in size. Major plants on the tree islands included redbay, dahoon (Ilex cassine), wax-myrtle (Myrica cerifera), coco plum (Chrysobalanus interior), laurelleaf greenbrier (Smilax laurifolia), grape (Vitis sp.), and several ferns [144].

In the Okefenokee Swamp, Georgia, Florida sandhill cranes occurred in a mosaic of freshwater wetland types including marshes, shrub swamps, swamp forests, and lakes. Three major marsh types included macrophyte marshes dominated by American white waterlily, goldenclub, and flattened pipewort, herbaceous marshes dominated by emergent graminoids including maidencane, broomsedge bluestem, and sedge, and mixed scrub-shrub marsh with stands of loblolly bay, pondcypress, fetterbush lyonia, and swamp titi [14]. Most of the marshes were formed by fires that burned away peat layers and created openings in formerly forested swampland. Most of the marshes in this area contained peat and had a low pH (reviewed by [12]).

BIOLOGICAL DATA AND HABITAT REQUIREMENTS

• LIFE HISTORY
• PREFERRED HABITAT
• FOOD HABITS
• MORTALITY
• MANAGEMENT CONSIDERATIONS

LIFE HISTORY:

• Description
• Social organization
• Courtship and mating
• Age at first reproduction
• Clutch size
• Incubation period
• Nest description
• Nest success
• Development and dispersal of young
• Life span
• Calendar dates for specific events
• Diurnal habit of species
• Home range size and spatial relationships
• Migration or seasonal movement

Social organization: The primary social units of sandhill crane populations are unmated adults, pairs, and family groups [137]. Unmated adults and family groups are largely separate during the breeding season but combine with unsuccessful pairs to form large aggregations during migration and overwintering (review by [136]). For migratory subspecies, spring staging areas are a primary area for courtship displays, renewing or maintaining pair bonds, and strengthening family group associations [51]. In an expanding greater sandhill crane population in Michigan, breeding pairs comprised 68% of the population [53].

At a fall staging area of greater sandhill cranes at Jasper-Pulaski Fish and Wildlife Area in northwestern Indiana, family groups were consistently dominant over nonbreeders in roosting and foraging sites. Family groups sometimes avoided large flocks, possibly because avoidance behavior may require less energy than aggressive behavior, or chances of separation may increase with flock size [90]. At fall staging areas on the Copper River Delta, Alaska, family groups of lesser sandhill cranes separated from the larger flock during daytime feeding but returned to the flock for roosting or to continue migration [51]. In the fall, Florida sandhill cranes in south-central peninsular Florida formed loose aggregations in favorable feeding areas; pairs and families tended to stay together and were somewhat isolated from other individuals [76].

Nonbreeders may make up a large portion of the overall sandhill crane population. At fall staging at the Jasper-Pulaski Fish and Wildlife Area, nonbreeding greater sandhill cranes comprised 59% of the population one year, and 65% another year [90]. In a population of greater sandhill crane at Grays Lake, Idaho, nonbreeders comprised 31% to 39% of the total population annually [31]. During the breeding season, nonbreeders often form large flocks, foraging and roosting together [87,105,133,142].

Courtship and mating: Sandhill crane mate selection occurs during elaborate courtship displays involving both dancing and vocalization (review by [136]). For midcontinental populations, pair formation occurs primarily during spring staging in Nebraska, often in wet pasture [137]. Pairs exhibit bonding behavior upon arrival on breeding grounds. Soon after returning to the breeding area, greater sandhill crane pairs at Grays Lake, Idaho, began preening with pieces of wet, decaying marsh vegetation which changed their plumage color from gray to reddish-brown [31].

Pairing is perennial, usually lasting as long as a mate lives ([138], review by [136]), though repairings do occur. Twenty-one pairs of Florida sandhill cranes were monitored from 1977 to 1988; 33% remained together while 67% changed mates (1 individual 4 times), for a total of 17 repairings. Fifty-three percent of the repairings occurred after the death of a mate, while 18% resulted from "divorce", with no mate mortality. Unproductive pairs did not necessarily divorce, particularly if they had produced young in the past [111].

Age at first reproduction: Greater sandhill cranes may pair as 2-year-olds but do not usually nest until the 3rd or 4th year (review by [90]). The mean age of successful first reproduction (young raised to independence) was 4.3 for greater sandhill cranes and 5.2 for Florida sandhill cranes [112]. Individuals from the midcontinental population of sandhill cranes nesting primarily in northwestern Canada and Alaska paired as early as age 3, but more commonly at ages 5 to 6. Sandhill cranes raised young to independence as early as age 5, but 76% of recruitment was from individuals >8 years old. Once pairs successfully raised young, they continued to be successful, though only approximately 25% of the population were successful parents at any given time [138]. For both Florida and greater sandhill cranes, >50% of offspring were produced by a minority (<30%) of adults [112].

Clutch size: Clutch size of sandhill crane nests ranges from 1 to 3, with 2 eggs most common (review by [136]). See the following publications for additional information on clutch size: [6,14,16,31,35,42,58,76,82,100,105,110,144,151,155,158].

While not common, Canada goose eggs were occasionally found in greater sandhill crane nests at Gray's Lake, Idaho [31].

Incubation period: Sandhill crane eggs are laid at 24- to 48-hour intervals [78] and are subsequently incubated approximately 28 to 31 days [31,78,127,151,158]. Incubation is performed by both parents [31,127,155]. Nests are rarely left unattended during incubation; if nests are unattended, it is usually the failure of the male to relieve the female after long periods of incubation [31]. Sandhill crane eggs hatch asynchronously [78,155]. The hatching process takes 24 to 36 hours [78]. In southern Michigan, greater sandhill crane eggs hatched on successive days [155].

Nest description: Sandhill crane nests usually consist of piles of whatever vegetation is readily available [16,42,127,135,151,158]. Consequently, nest composition varies by location. Cow manure may also be used in nest construction [31,135]. See nest site descriptions in Preferred habitat for specific materials used in nest construction.
	Sandhill crane nest in southwestern Montana. Photo by Katharine Stone.

The size of sandhill crane nests varies within and between subspecies (for nest dimensions, see: [31,42,104,127,151,155,156,158]); nests of both the Canadian [158] and lesser [16] sandhill cranes ranged from minimal piles of vegetation to large haystacks [158]. Greater sandhill cranes in Idaho took 1 to 7 days to construct their nests [31], while lesser sandhill cranes may complete nest building in a few minutes [158].

Sandhill crane nests are often placed at the edges of wetlands [14,31,104] or on islands or hummocks surrounded by water [105,159], though they are occasionally found on top of old muskrat houses [31,158]. Sandhill cranes prefer relatively undisturbed areas for nest placement [31,150].

Nest success: Nest success is defined as having at least one egg hatch successfully. Nest success is variable, with documented nest success ranging from 37.5% to 87%.

Predation is the most common reason for nest failure [14,16,31,35,64,65,81,82,100]. In the Okefenokee Swamp, predation by raccoons was the reason for 75% (60 nests) of unsuccessful Florida sandhill crane nests [14]. At Malheur National Wildlife Refuge in southeast Oregon, 69% of 506 greater sandhill crane nests were destroyed by predators [64,65]. In northeastern California, 54% of 30 greater sandhill crane clutches were destroyed by predators, mostly coyotes [82]. See Predation for more information on this topic.

Weather, including temperature and precipitation, may also impact nest success. Greater sandhill crane nest success was higher in relatively warmer springs at Malheur National Wildlife Refuge in southeast Oregon [64,65]. In south-central peninsular Florida, most variation in percentage of pairs with young was explained by rainfall in January and March, with January rainfall stimulating reproduction and March rainfall reducing productivity [76]. At the Okefenokee Swamp, Georgia, chick mortality from drowning and pneumonia was suspected in a year with prolonged rainfall and peak water levels at the time of hatching. Water levels fluctuating either above or below normal led to low recruitment rates [14].

Low water levels in drought years usually reduce sandhill crane nest success. Drought reduces water levels around nests, which may increase predation risk and reduce the availability of food and drinking water [9,33,82]. In northeastern California, drought may have contributed to greater sandhill crane pairs not nesting, high predation rates at nests, and subsequently low nest success and low recruitment [82]. In Idaho, low moisture and hard summer frosts were linked to a decrease in invertebrate abundance, which may have led to low chick recruitment [9]. In north-central Florida, when marsh water levels were unusually low, Florida sandhill crane nesting efforts were reduced, and mortality following fledging was high (83%) [112]. Low recruitment was observed at fall migration stopovers in Colorado and wintering grounds in Mexico in years where drought persisted at breeding grounds [33]. In contrast, Cuban sandhill cranes had higher reproductive success when October and November precipitation was lower than average [42].

Though drought may often result in low nest success, at the other extreme, flooding may also result in nest failure [14,35,64,65,81,100]. Nest failure may also result from abandonment [35,64,65,81,82], often in response to human [14,31,148] and even researcher [31,35,65,151,158] disturbance. Nests may also fail due to infertile [35,64,65,81,82,100] or rotten [16,35,100] eggs. Sandhill cranes may abandon nests due to mate mortality [31].

Human development may impact sandhill crane nest success. In southeastern Florida, Florida sandhill cranes nested in both isolated wetlands adjacent to either pastures, prairies, or pine flatwoods, or in littoral zones of man-made ponds and lakes in suburban developments. Most of these artificial wetlands received runoff from golf courses, streets, and lawns, facilitating encroachment of cattails. There were 42 nesting attempts in natural wetlands and 31 attempts in developed wetlands. Sandhill cranes in natural wetlands initiated nesting more than a month earlier and were more successful breeders (67% vs. 26%; P<0.01) than those in developed wetlands. Sandhill cranes in natural wetlands also produced more fledglings/pair (0.86 vs. 0.32) and had more fledglings/pair survive to independence (0.45 vs. 0.16) than those in developed wetlands. The results of this study suggest that developed wetlands likely represent habitat sinks and should not be promoted as mitigating sandhill crane habitat [147].

Land management practices also impact sandhill crane nest success. At Malheur National Wildlife Refuge, haying, livestock grazing, and predator control did not influence nest success, while prescribed fire did (See Indirect fire effects). Other factors reported to influence nest success included water depth at nest, vegetation type around nest, and nest concealment [64,65].

Renesting: In some populations, it is fairly common for sandhill cranes to attempt renesting if the first nest fails. In a population of greater sandhill cranes at Grays Lake, Idaho, renesting occurred when clutches were lost prior to mid-incubation [31]. In this same area, renesting attempts ranged from 1.5% to 10.5% of all nests over 4 years; 2 pairs renested twice in the same season, apparently in response to researcher disturbance [4,9].

Renesting rates are higher for Florida sandhill cranes, which one author attributes to the longer nesting period in this area compared to other areas. Over 4 years of study at Paynes Prairie, Florida, 78% of birds that abandoned nests or had eggs removed from their nests renested [110]. In the Green Swamp of Florida, of 111 Florida sandhill crane nests observed over 2 years, 21% were second efforts [35]. One year, at the Okefenokee Swamp, Georgia, 70% of the Florida sandhill cranes that were unsuccessful at their first attempt renested; some nested a third time (29% one year, 40% in another). The incidence of renesting was closely tied to water levels, with low water levels associated with drought leading to few renesting attempts. The mean nest success rates for first attempts was 59%; for second attempts, 54%. However, the mean survival rate of broods from first nests (40%) was significantly lower than survival from second nests (56%) (P<0.05) [14].

Unsuccessful sandhill crane pairs in southeastern Saskatchewan [21] and on the Yukon-Kuskokwim Delta, Alaska [16] did not renest following nest failure.

Development and dispersal of young: After hatching, sandhill crane chicks are mobile relatively quickly and are capable of flight by the late summer or early fall. If they survive, sandhill crane chicks generally stay with their parents through their first winter, reaching independence the following spring.

Movements or behavior after hatching: Sandhill crane chicks are mobile soon after hatching. They are able to walk after 24 hours, allowing the family to move to upland areas to forage [78]. Families usually return to nesting areas to roost at night [78,127]. In southern Michigan, greater sandhill crane chicks remained in the nest about 48 hours. Young could swim soon after hatching and often had to swim after leaving the nest. Parents led chicks toward drier land where they fed for several weeks [155].

Recently hatched sandhill crane chick. Photo by Bill West, US Fish and Wildlife Service.

Near Grays Lake, Idaho, some greater sandhill crane broods moved within 24 hours after the second young hatched, while other broods remained at the nest for several days. Many broods remained within 600 feet (200 m) of nests for the first week after hatching. In some instances, parents divided and tended the young; the male moved the first chick away from the nest while the female tended the second. Adults often kept chicks separated by as much as 300 feet (100 m) [31].

Relationships between sandhill crane siblings vary. Near Grays Lake, Idaho, aggressive actions between greater sandhill crane siblings usually occurred during feeding activities. Sibling dominance was often determined in 1 fight, and the defeated chick would remain submissive throughout the preflight period [31]. Sibling aggression was also noted in greater sandhill crane chicks in the Shasta Valley of California, where the stronger chick would drive off the weaker one [127]. One author, noting that nearly half of the greater sandhill crane chicks per brood near Grays Lake, Idaho, died prior to flight age, suggested that sibling rivalry and subsequent starvation led to chick mortality [31]. In contrast, Florida sandhill crane chicks in south-central Florida were usually closely associated with each other and showed no visible signs of sibling dominance or aggressiveness. There was no evidence of parents trying to separate chicks [75].

Gregariousness begins in August when young start flying; family groups of migratory subspecies vacate territories to join post-breeding flocks, which gather annually at specific premigration fall staging areas [31]. Prior to migrating, families in southern Michigan stayed in the general area of the nest, and then began to congregate in large groups as fall approached [155]. Families in the Rocky Mountain population of greater sandhill cranes minimized fall and winter harassment of young by other sandhill cranes by remaining detached from large flocks; integration increased as juveniles matured through the winter [33].

Flight: Greater sandhill cranes near Grays Lake, Idaho were able to fly at 67 to 75 days old [31]. In southern Michigan, greater sandhill crane young learned to fly at about 80 days old [155]. The young of northern subspecies of sandhill crane develop faster to facilitate their earlier migration by late August or early September [158].

Chick survival/recruitment: Mortality prior to fledging is high [31]. The probability of surviving from hatching to independence was 0.566 for 69 Florida sandhill cranes [112]. See [33] for a comprehensive review of recruitment rates and fall and winter brood sizes for populations of sandhill cranes throughout their range. At fledging, brood size for Florida sandhill cranes averaged 1.12 fledglings/pair at the Okefenokee Swamp, Georgia [14], and 1.35 fledglings/pair for greater sandhill cranes near Grays Lake, Idaho. Moderate juvenile mortality also occurs during fall migration [31]. For midcontinental sandhill cranes wintering in Mexico, 18% of families had 2 young on wintering grounds [32]. In 20 years of surveys of the Rocky Mountain population of greater sandhill cranes stopping over in the San Luis Valley of south-central Colorado and wintering in south-central New Mexico, 76.3% of broods had 1 young, 23.6% had 2, and 0.1% had 3 [33].

A number of factors may limit recruitment rates, including predation [14,33,81], drought [14,33,81], and the availability of food and water [33]. Some authors hypothesize that eastern populations of sandhill cranes have high recruitment rates because they breed in areas with relatively stable habitat (i.e., less chance of drought, stable precipitation) [33]. Low recruitment is one factor limiting population recovery after decline [81]. See Management considerations for more information on this topic.

Independence: Sandhill crane young generally stay with their parents through their first winter [31,33]. Juveniles of the resident population of the Florida sandhill crane in north-central Florida remained with parents for 9 to 10 months [112,113]. The young of migratory subspecies remain with their parents through fall migration and wintering. Over 90% of juveniles from the migratory midcontinental population of sandhill cranes stayed with parents until late April the year after hatching [137]. Similarly, over 90% of juveniles from the Rocky Mountain population of greater sandhill cranes separated from adults in March and April after hatching [33]. Few returning pairs of greater sandhill cranes near Gray's Lake, Idaho, were accompanied by yearlings [31]. Radio-tracked juveniles from the Rocky Mountain population of greater sandhill cranes that separated from their parents during spring migration summered with other nonbreeding cranes within 2 to 39 miles (4-62 km) of their natal areas [34]. Greater sandhill crane juveniles in the Shasta Valley of California [127] and in Michigan [155] returned with their parents to their natal territory but were eventually driven away, forming a flock with other nonbreeding birds.

Life span: Records from captive birds suggest that sandhill cranes may live 20 to 30 years. Marked sandhill cranes in the wild were at least 14 years old ([78], review by [124]). Florida and greater sandhill cranes >19 years old were observed successfully producing young [112].

Calendar dates for specific events:

Arrival on breeding territories: Migratory sandhill cranes return to breeding territories in the spring; the exact dates vary by subspecies and location. In northern areas, breeding territories may still be snow-covered when sandhill cranes arrive. Lesser sandhill cranes returning to Alaska may encounter frozen lakes and rivers [16,91] or snow >10 inches (25 cm) deep [91]. Greater sandhill cranes in northwest Ontario arrive in mid-April and congregate in ploughed fields until snow melts, then move to breeding territories [36]. In Idaho, nest initiation may begin as soon as snow melts from nesting areas [6].

Sandhill cranes often encounter snow upon arrival to breeding grounds. Photo courtesy of US Fish and Wildlife Service.

Nesting dates: Nest initiation varies by subspecies and location. Resident subspecies may initiate breeding much earlier than migratory subspecies.

Sandhill crane nest initiation may be influenced by several factors, including temperature, availability of snow-free sites, water levels, and social interactions. In southern Michigan, greater sandhill cranes laid eggs earlier in relatively warm springs than in relatively cold springs [155]. Breeding was delayed by late spring cold temperatures at the Walker Bay Field Station, Northwest Territories [41]. On the Yukon-Kuskokwim Delta, Alaska, few snow-free areas may be available when lesser sandhill cranes return, limiting nest site selection [16]. In the Okefenokee Swamp, Georgia, nesting chronology varied by year and was strongly influenced by water levels; nest initiation was later in drought years [14]. In the Green Swamp of Florida, Florida sandhill cranes in large marshes that also supported migrant greater sandhill cranes nested later than those in smaller marshes without migrant cranes. The author hypothesized that resident cranes on larger marshes spent more time in territorial and social activities and consequently nested later [35].

Egg hatching: Hatching dates vary across the range of sandhill cranes, with nonmigratory subspecies generally hatching earlier than migratory subspecies.

Staging/migration: Initial staging prior to fall migration occurs from late summer to early fall when young start flying [31,45,80,106,148,158]. Additional stopover or staging areas may be used along the way from fall to mid-winter [89]. Sandhill cranes arrive on wintering grounds in late fall to early winter [13,114,127]. Spring staging and departure generally occur from February to early April [13,69,89,114,148].

Diurnal habit of species: In general, sandhill cranes roost at night and forage during the day [51,61,62,134,155]. Midday loafing and preening may occur, either near foraging areas or at roost sites [155]. Pairs with young follow the same diurnal pattern but tend to roost and forage near the nest site until young are old enough to fly [78,127]. Staging and migrating sandhill cranes generally roost at night, leave roosts near sunrise, feed in agricultural fields during the day, and return to roosts at sundown [61,62,134].

Weather conditions may impact daily behaviors of sandhill cranes. At a spring staging concentration of the midcontinental population in the Platte River Valley of Nebraska, cranes left roosts later on days with fog or precipitation [128]. In the fall, sandhill cranes staging at the Jasper-Pulaski Fish and Wildlife Area in northwestern Indiana tended to stay at roost sites on cold, windy days. Sandhill cranes would often use a secondary roost (e.g., pasture) during the day, especially in inclement weather [89]. On the Copper River Delta, Alaska, staging lesser sandhill cranes avoided completely open roost sites during severe storms [51].

Home range size and spatial relationships: Home range size of sandhill cranes varies among subspecies, locations, and seasons. Proximity and spatial arrangement of preferred nesting, roosting, and foraging habitats may impact home range size.

Migratory subspecies: During the breeding season, pairs of migratory subspecies maintain a breeding territory, with most pairs showing high fidelity to the breeding territory [8,16,31,53,127,155,158]. Greater sandhill cranes at Grays Lake, Idaho, returned to the same territories every year; the distance between old and new nests was seldom >1,300 feet (400 m). Pairs aggressively defended their territory, particularly in the prenesting period. Territories included nest and roost sites, feeding meadows, and open water used for drinking and as escape cover. Pairs patrolled territory boundaries and bluff-charged trespassing sandhill cranes. Most conflict occurred in areas of territorial overlap or near boundaries. Territorial conflicts were not observed during the brooding or post-brooding periods. Use of territory depended on available resources, location of nest (shallow or deep water), loss of nests or broods, and human disturbance. Sandhill cranes with territories far from agricultural fields for foraging abandoned their territory earlier in the summer than those close to agricultural fields [31].

During the breeding season, roosting and foraging occur within the boundaries of the breeding territory. During migration and staging, distances between roosting and foraging sites may be as far as 5 miles (8 km) [134,158], and may depend on the availability and distribution of roosting and foraging habitat [62,106]. Wintering lesser sandhill cranes may fly 1 to 5 miles (2-8 km) from roosts to grain fields for feeding [158]. Seven radio-tagged sandhill cranes staging in North Dakota had overall activity ranges of 22,842 to 105,877 acres (9,244 to 42,847 ha) over 24 to 48 days; the range of distances was attributed largely to that year's spatial arrangement of roosting and foraging habitat [106].

Breeding and nesting territories range in size. In the Shasta Valley of California, breeding territory size ranged from 20 to 60 acres (8-24 ha), with some territories much larger [127]. At Grays Lake, Idaho, mean nesting territory size was 42 acres (17 ha), ranging from 25 to 57 acres (10-23 ha). In Michigan, 5 to 7 breeding pairs of greater sandhill cranes occupied a 260-acre (105 ha) area of marsh. Breeding territories ranged from 8 to 67 acres (3-27 ha) and averaged 43.5 acres (17.6 ha) [158]. Five pairs of greater sandhill cranes at Grays Lake, Idaho, had a mean nest territory size of 42 acres (17 ha) [31]. In north-central Colorado, greater sandhill crane nesting territories were much larger than those reported from other areas, ranging in size from 158 to 561 acres (64-227 ha) [130].

Due to their territoriality, sandhill crane nests tend to be located at a distance from other nests, though this distance varies. At Grays Lake, Idaho, mean distance between greater sandhill crane nests was 1,414 feet (431 m) [31]. In the Interlake region of central Manitoba, active sandhill crane nests were found no closer than 1,969 feet (600 m) from each other [105]. On the Yukon-Kuskokwim Delta, Alaska, lesser sandhill crane nests ranged from 909 to 5,167 feet (277-1,575 m) apart [16]. In eastern Siberia, lesser sandhill cranes nests were as far apart as 17,300 feet (5,280 m) [159]. Vegetative cover or other visual barriers such as topography may explain the close proximity of some nests; in the Interlake region of central Manitoba, seldom was more than 1 nest found in the same muskeg unless there was some sort of visual barrier between nest sites [105].

Sandhill crane nest density varies across the landscape and may not be consistent from year to year in the same area. At Gray's Lake, Idaho, greater sandhill crane nest density ranged from 0.038 nests/ha to 0.054 nests/ha for 578 nests over 4 years [4]. In an expanding greater sandhill crane population in Michigan, nest density ranged from 0.5 nests/km² to 0.8 nests/km² over 12 years [53]. One of the difficulties in assessing nesting density is defining the sampling area, as sandhill crane nests may not be evenly distributed across a landscape. For example, a 1,050,198 acre (425,000 ha; 4,250 km²) area of the Interlake region of central Manitoba had a breeding density of 1.3 sandhill crane pairs/100 km², though one 69,190 acre (28,000 ha; 280 km²) section had the highest concentration with a density of 7.5 sandhill crane pairs/100 km² [105]. See [105] for density estimates of sandhill crane pairs breeding in boreal and subarctic regions of North America.

There is little information available regarding the home range of sandhill crane chicks. One study examined the summer movements of families with prefledging chicks at the Seney National Wildlife Refuge, Upper Peninsula, Michigan. Home ranges for 8 prefledging chicks ranged from 89 to 959 acres (36-388 ha), averaging 390 acres (158 ha); small home ranges were associated with drawn-down pools or had an agricultural field adjacent to the nesting and roosting marsh (both provide ample food sources). Large home ranges were associated with the need to travel 1 to 4 miles (2-6 km) to pools or fields that offered better food sources than nesting areas, though the movement may have increased predation risk [100].

Nonmigratory subspecies: Because they spend the whole year in one geographic area, nonmigratory subspecies maintain more easily identifiable year-round home ranges than migratory subspecies. In resident populations of the Florida sandhill crane in north-central Florida, home range differed by age of bird and season. Over 3.1 years, adult pairs had estimated home ranges of 625 acres (253 ha) before nesting, 445 acres (180 ha) while nesting, and 306 acres (124 ha) after nesting. Over 1.9 years, subadults had estimated home ranges of 825 acres (334 ha) in the prenesting season, 1,552 acres (628 ha) in the nesting season, and 198 acres (80 ha) in the postnesting season. The large home range size for subadults during the nesting season was attributed to the territoriality of adults defending nesting areas [113].

Over 2 years, a population of Florida sandhill cranes in the Okefenokee Swamp, Georgia, had a mean annual home range size of 230 ± 64 acres (93 ± 26 ha) for adults and 993 ± 423 acres (402 ± 171 ha) for subadults; among subadults, home range size decreased as sandhill cranes aged. Adult home ranges did not overlap, while subadult home ranges normally overlapped other subadult and adult home ranges. For both adults and subadults, home range size increased in summer. Water level fluctuations influenced seasonal movements but did not affect fidelity to established home ranges. Movement of subadults was 4 times greater than that of adults (P<0.05). Eight of 11 subadults remained within 2.5 miles (4 km) of their capture and exhibited home range movements. Two juvenile cranes dispersed linear distances of 5.6 to 6.5 miles (9.0-10.5 km) from their natal areas, and did not establish a stable area of residence in their first year. None of the monitored cranes moved outside the Okefenokee Swamp. Compared to other populations of Florida sandhill cranes, home range size was smaller for this population, which the authors attributed to the to the exclusive use of marshes and nonuse of upland pastures [11].

Like migratory subspecies, nonmigratory subspecies maintain breeding territories that are often used repeatedly [144,151,158]. The same nest may be used repeatedly ([151], review by [150]), or several inactive, or "dummy", nests may be found in close proximity to active nests [144,151]. The inactive nests may be used by adults and chicks for additional roosting or may act to confuse potential predators (review by [150]).

Florida sandhill crane nests were as close as 236 feet (72 m) at the Green Swamp, Florida [35]. At the Loxahatchee National Wildlife Refuge in Florida, active Florida sandhill crane nests were generally 1,320 feet (402 m) apart, though 2 nests were only 449 feet (137 m) apart [144]. In southeastern Mississippi, the shortest distance between active Mississippi sandhill crane nests was 2,640 feet (805 m) [151]. In Cuba, the average distance between Cuban sandhill crane nests was 9,345.6 feet (2,848.5 m) [42]. As with migratory subspecies, vegetative cover or other visual barriers such as topography may explain the close proximity of some nests; Mississippi sandhill cranes nested closer to each other (as close as 0.5 mile (0.8 km)) when savanna clearings were separated by forested areas (review by [150]). In the Okefenokee Swamp, Georgia, Florida sandhill crane density was positively correlated with the volume of herbaceous cover within individual marshes (r = 0.93, P<0.001); marshes with low crane density had <5% cover of herbaceous vegetation [12].

In the Green Swamp of Florida, density of 111 Florida sandhill crane nests over 2 years was 2.5 nests/ha [35]. In the Okefenokee Swamp, Florida sandhill crane density averaged 1.9 cranes/km² but was not uniformly distributed, with density ranging from 0.4 to 6.1 sandhill cranes/km²; one region comprised 26% of the marsh habitat but supported 65% of the sandhill crane population [12].

Migration or seasonal movements:
Migratory subspecies: Migratory cranes generally stage, or congregate, in repeatedly used areas in the fall and then proceed to traditional wintering grounds (see General distribution for specific migratory routes and wintering areas). Sandhill cranes also congregate at spring staging areas prior to departing for northern breeding grounds. The length of stay at staging areas is variable; individuals may stay only 1 to 2 days at the Copper River Delta, Alaska, but stay weeks in Nebraska [51]. Radio-tagged sandhill cranes from the midcontinental population stayed in the Platte River Valley an average of 26 (1978) and 32 (1979) days after radios were attached in late February or early March [70].

Migration occurs mostly during the day ([34,51], review by [124]), though sandhill cranes may migrate at night [51]. Daily distances traveled may reflect local conditions such as weather and food availability. One review states that migratory sandhill cranes travel 160 to 240 miles/day (250-380 km/day) [124]. Radio-tagged sandhill cranes have moved as much as 342 miles/day (550 km/day) from breeding grounds in east-central Minnesota and northwestern Wisconsin to Florida wintering areas (US Fish and Wildlife Service unpublished 1978, 1980 reports cited in [88]). Greater sandhill cranes migrating from Michigan to Indiana traveled between 40 to 240 miles/day (60-380 km/day), with flight speed ranging from 18 to 34 miles/hr (29-54 km/hr); the fastest speeds and longest distances were achieved when skies were sunny and clear and winds were from the northwest [100]. Another reference states that sandhill cranes fly about 32 to 35 miles/hour (51-56 km/hr) [157]. Individuals (mostly juveniles) from the Rocky Mountain subpopulation of the greater sandhill crane traveled >500 miles (800 km) in 2 to 3 days of diurnal flying at elevations >8,900 feet (2,700 m); elevations exceeded 12,100 to 13,100 feet (3,700-4,000 m) when individuals crossed major mountain ranges (Drewien unpublished data cited in [34]). Average flight height of migrating lesser sandhill cranes averaged 906.2 feet (276.2 m) in spring and 526.9 feet (160.6 m) in fall, with spring heights significantly higher (P=0.05) [51].

Sandhill cranes show high fidelity to historical staging grounds and migratory routes [34,51,89,100,106,148], and often the presence of flocks on the ground encourages other flocks to land [51,106]. Individuals (mostly juveniles) from the Rocky Mountain subpopulation of the greater sandhill crane showed high fidelity to migratory paths and specific locations during both the breeding and wintering seasons over successive years, suggesting that juveniles learned suitable habitat and migratory routes from their parents [34]. Greater sandhill cranes migrating from the Upper Peninsula of Michigan showed strong fidelity to historical staging areas in Indiana that appeared to be well outside of their migratory route. The author hypothesized that the staging area was established when greater sandhill crane breeding ranges were more extensive, prior to human disturbance and habitat destruction [100]. At the Jasper-Pulaski Fish and Wildlife Area in northwestern Indiana, sandhill cranes consistently returned to fields that had received decades of use and ignored fields that appeared to be identical even if they were closer to the roost. Sandhill cranes returned to the same fields even as crop production switched among corn, soybeans, and winter wheat (Triticum sp.) [89].

Weather may impact the timing of sandhill crane staging and migration. Drought conditions at the end of summer may cause cranes to congregate earlier, leading to large concentrations of foraging flocks as food becomes scarce [80]. Falling temperatures may also prompt congregation and departure in the fall. In southern Michigan, greater sandhill crane migration began when the mean temperature was <36 °F (2 °C) for more than a day, ice formed on ponds, and the soil surface began to freeze [155]. Freezing conditions in central Wisconsin also prompted greater sandhill cranes to migrate south [45].

During staging, sandhill cranes may extend their stay at a specific area if they encounter poor weather such as heavy rainfall, strong headwinds, fog, or heavy cloud cover. Sandhill cranes may also bypass staging areas altogether if they encounter favorable tailwinds and clear skies [51]. Inclement weather may prompt stops along migratory routes [51,157] or may cause cranes to move south to avoid conditions such as subfreezing temperatures [13]. Heavy rainfall forced wintering sandhill cranes in Georgia to abandoned the swamp they were using [13,31]. Record cold temperatures in New Mexico in 1971 (-4 to -8 °F (-20 to -22 °C)) caused a 40% decline in local wintering greater and lesser sandhill crane populations [31].

Warming temperatures may prompt the return to breeding grounds in the spring, with variations in annual spring temperatures leading to variations in arrival dates [28,45,155]. Greater sandhill cranes arrived on breeding grounds in southern Michigan when the mean daily temperature reached 36 °F (2 °C) [155].

Nonmigratory subspecies: Nonmigratory subspecies may show seasonal movements within their range, though movement distances may be relatively small. In a population of the Florida sandhill crane in the Okefenokee Swamp, Georgia, seasonal movements involved shifts that were mostly <0.6 mile (1 km). Adults travelled daily from roosts to feeding sites (mean distance of 1,475 ft (450 m) ± 920 (280) SE) and to defend territories [11].

Climate: Sandhill cranes encounter a variety of climatic conditions across their geographic range. Nonmigratory subspecies complete their life history in generally warm climates like that of Florida, where winter temperatures are mild, with lows in January and February of 46 to 50 °F ( 8-10 °C), and summers are hot and humid, with high temperatures in July and August of 86 to 90 °F (30-32 °C) [113]. Migratory subspecies face a broader range of climatic conditions, breeding in places such as eastern Siberia, where summer temperatures range from 25 to 72 °F (-4 to 22 °C) and snow and ice may be present at the beginning of the breeding season [159]. Overwintering of migratory subspecies occurs in warmer climates, like the mild winter climate along the Gulf Coast of Texas [57].

Elevation: Sandhill cranes are not restricted to any particular elevation, and migratory individuals may occupy habitats at a wide range of elevations throughout the year.

Habitat of migratory subspecies:

• Breeding season habitat
• Staging and migrating habitat
• Wintering habitat

• Canadian sandhill crane
• Greater sandhill crane
• Eastern population
• Rocky Mountain population
• Central Valley population
• Lesser sandhill crane
• Unidentified subspecies

Canadian sandhill crane: As of 2009 little information is available on the preferred breeding habitat of Canadian sandhill cranes, and all information presented is from reviews. Breeding habitat includes boreal forests and aspen parklands [124], muskeg and other shallow wetland communities, open and forested bogs, and other boreal forest wetland types [102]. In the southern portion of their range, Canadian sandhill cranes nest in large open marshes often surrounded by open fields or prairies. Farther north, Canadian sandhill cranes nest in muskeg country or in open marshes surrounded by forest [158].

Greater sandhill crane: Greater sandhill cranes primarily use wetland habitat for breeding ([45,53,87,97,98,127,155,158], review by [124]), though the specific type of wetland varies regionally. In some areas, breeding habitat includes a mixture of wetlands and farmlands [45,97,98,127,133] or wetlands and uplands [9,45,53,155]. Breeding habitat for the greater sandhill crane is discussed for the Eastern, Rocky Mountain, and Central Valley populations:

Eastern population: Breeding habitat for greater sandhill cranes in the eastern or Great Lakes region often contains bog plant communities [158]. Mosaics of upland and wetland habitat are also common breeding habitat in Michigan [8,53,155]. At the Seney National Wildlife Refuge, Upper Peninsula, Michigan, the sandhill crane breeding area was 62% wetland and 38% upland habitat [8]. In an area of greater sandhill crane population expansion in Michigan, 10% of the breeding area consisted of nonforested wetlands [53]. In Wisconsin, the highest density of breeding greater sandhill cranes occurred in the central sands region where the greatest mixture of wetlands and agricultural lands occurred; emergent wetland was the most important habitat component [133]. In one area, wetlands used for breeding ranged in size from 20 to 7,005 acres (8-2,835 ha) [58].

Nest sites: Greater sandhill crane nests are often surrounded by open water. Sedges, bulrushes, grasses, broadleaf cattail, narrow-leaved cattail (Typha angustifolia), and common reed (Phragmites australis) are often the predominant vegetation surrounding nest sites (review by [158]). In Wisconsin, greater sandhill cranes nested in isolated, shallow water bodies >40 acres (16 ha) [45]. Of 174 nests observed in southern Michigan, 62 nests were in sedges, 66 were in broadleaf and narrow-leaved cattails, 29 were in soft-stem bulrush, 10 were in swamp loosestrife (Decodon verticillatus), 4 were in fine dead grasses, 2 were in rushes, and 1 was in a mixture of plants [158]. Primary marsh plants in greater sandhill crane nesting areas in southern Michigan included broadleaf cattail, broadfruit bur-reed, broadleaf arrowhead (Sagittaria latifolia), annual wildrice (Zizania aquatica), redtop (Agrostis gigantea), reedgrass (Calamagrostis spp.), and common reed. Marshes were surrounded by tamarack forests and shrubs such as red-osier dogwood (Cornus stolonifera), silky dogwood, gray dogwood (C. paniculata), willow, poison sumac (Toxicodendron vernix), and wild rose (Rosa spp.). Isolation was also provided by tamarack, a few small groups of quaking aspen, and thick stands of common reed [155].

In northwestern Ontario, greater sandhill cranes used a variety of habitats for nesting, including cattail marshes, wet meadows with scattered willows, dry hayfields, and bogs and fens with scattered black spruce and tamarack [36]. In Maine, a single sandhill crane nest was located at the edge of a small open pool. The nest was surrounded by cattails and adjacent to a sedge- and sphagnum-dominated lakeside fen. The nest was constructed entirely of cattails [104].

Foraging and roosting: Greater sandhill cranes breeding in southern Michigan roosted in shallow water in marshes. Paired individuals fed in the heart of the marsh, near nest sites. They occasionally flew a short distance to the closest upland area to feed, though only for a few hours. Nonbreeding birds roamed more when foraging, often feeding in fields [155].

Rocky Mountain population: Breeding habitat for the Rocky Mountain population of greater sandhill cranes includes wetlands and marshes [6,9,25,31,101], wet mountain meadow drainages [15,25,101,148], and mosaics of riparian and agricultural habitats [97,98]. In some areas, greater sandhill cranes use sagebrush uplands in the breeding season for foraging and roosting [9,15,101]. In northern Utah and southwestern Wyoming, greater sandhill crane used pastures (55%), small grain fields (19%), riparian areas (8%), alfalfa fields (6%), corn fields (3%), and other plant communities (9%) in the breeding season [97,98].

Nest sites: The majority of research on the Rocky Mountain population of greater sandhill cranes is from Grays Lake, Idaho. Early studies in this area (1973) found 92.5% of 337 nests located in vegetation dominated by 16 species. Baltic rush was the most important nesting cover, followed by sedges and hardstem bulrush [31]. A later study (2007) also found baltic rush dominating greater sandhill crane nest sites [64,65].

A third study categorized vegetation by height, with short emergent hydrophytes at the majority of nest sites. While vegetation types were not defined in terms of plant species composition, the majority of the study area was dominated by a broadleaf cattail-bulrush marsh [6].

Thirty-six greater sandhill crane nesting sites in eastern Idaho were dominated by rushes, sedges, broadleaf cattail, and willows. Nests were also found in a waterlily bed, in reed canarygrass (Phalaris arundinacea), and on a beaver lodge [101]. Two greater sandhill crane nests in Yellowstone National Park, Wyoming, were located in riverfront marshes with dense cover of rushes [25].

Greater sandhill cranes in northwestern Colorado nested along small, willow-lined drainages, usually one pair to a drainage. Nest sites were commonly separated by ridges that paralleled the streams. Nests were always within 3 feet (1 m) of slow moving water and were surrounded by dense cover, usually willow. Nests were made of willow twigs, mainly obtained from beaver cuttings, as well as some grass [15].

Foraging and roosting: At Grays Lake, Idaho, greater sandhill cranes foraged along marsh edges and at upland feeding sites. Vegetation at feeding sites was dominated by the nonnative pasture grasses timothy (Phleum pratense), Kentucky bluegrass (Poa pratensis), and smooth brome (Bromus inermis), along with sticky purple geranium (Geranium viscosissimum) and western yarrow (Achillea millefolium) [109]. In this same area, greater sandhill cranes also foraged in upland sagebrush habitat in both the spring and fall, though most foraging occurred in wet meadows [9]. In eastern Idaho, foraging sites adjacent to nesting areas were primarily composed of sagebrush, cinquefoil, rabbitbrush, bunch grasses, upland forbs, quaking aspen, and cottonwoods [101].

In northwestern Colorado, greater sandhill crane families used both sagebrush ridges and aspen stands for roosting and loafing. Individuals were occasionally found as high as 66 feet (20 m) in the trees [15].

Central Valley population: Greater sandhill cranes in the Central Valley population breed in wet meadows [77,87,127], irrigated pastures [127], marshes [64,65,87], or wetlands [84,86]. They often use a mixture of wetland and upland habitat [77,84]. In the Shasta Valley of California, breeding season habitat was mainly large, open irrigated pastures, especially those that were poorly drained and had small artificial wetlands adjacent to them [127]. In Oregon, most greater sandhill crane pairs occurred on wet meadow-marsh habitats [87]. Breeding habitat in southeastern Oregon included idle, grazed, and hayed wetlands [86].

Nest sites: At the Malheur National Wildlife Refuge, Oregon, 90% of greater sandhill crane nests were in wetlands with coarse emergent vegetation comprised mostly of hardstem bulrush, broadleaf cattail, and broadfruit bur-reed [83]. In eastern Oregon vegetation around nest sites included spikerush, reed canarygrass, broadfruit bur-reed, hardstem bulrush, saltgrass (Distichlis spicata), swollen beaked sedge (Carex rostrata), or flooded black greasewood. One nest was located along a beaver pond, and another was on an unvegetated island [84].

In northeastern California, most greater sandhill crane nests were in open wet meadows. Of 48 nests, 44% were in rushes or spikerush, 19% in broadfruit bur-reed, 10% in grasses, 8% in sedges, 6% in hardstem bulrush, and 2% in broadleaf cattail [82]. In the Shasta Valley of California, greater sandhill cranes seemed to prefer tall marsh vegetation, such as bulrush or cattails, at nesting sites. Wetlands used for nesting were as small as 0.5 acre (0.2 ha) [127].

Lesser sandhill crane: Lesser sandhill cranes breed in arctic tundra ([16,70,91,119,158,159], review by [124]), muskeg, northern coastal dune [158], marsh, and sedge/grass meadow [16] plant communities.

Nest sites: Lesser sandhill crane nest sites are located within tundra vegetation and are often placed at the top of tundra banks or sandy knolls [158]. Lesser sandhill crane nests on the Yukon-Kuskokwim Delta, Alaska, were found on 7 topographic features: raised mounds in meadows, wet marsh meadows, narrow isthmuses between ponds, low wet islands, slough banks, islands in marshes, and dry islands in ponds. It was suggested that nest location was determined more by the few snow-free areas available upon arrival than specific topographic features [16].

One nest on a tundra bank near Bethel, Alaska was found among moss, grass, and black crowberry, and was constructed of pieces of cotton sedge, grass, and moss [158]. In eastern Siberia, lesser sandhill crane nests were primarily surrounded by sedges. Shrubs (birch (Betula spp.), Labrador tea (Ledum spp.), diamondleaf willow (Salix pulchra), polar willow (S. polaris)), mosses, tussocks, and tundra forbs were also present [159].

On the Yukon-Kuskokwim Delta, Alaska, most lesser sandhill crane nests were located on wet marsh sites or in sedge/grass meadows. Nests in marshy areas were located on some type of mound at least slightly higher and drier than the surrounding area. Dominant plant species around nests included polargrass (Arctagrostis latifolia), red fescue, sand ryegrass (Leymus arenarius), Lyngbye's sedge (Carex lyngbyei), looseflower alpine sedge (C. rariflora), dwarf birch, black crowberry, and sphagnum. Nests were made primarily of grass or sedge, but also included twigs of oval-leaf willow (Salix ovalifolia), unidentified woody roots, and old stems of grassleaf sorrel (Rumex graminifolius) [16].

Foraging: Upon spring arrival in the Northwest Territories, lesser sandhill cranes foraged in snow-free areas on the tops of eskers. As snow melted, foraging occurred further down esker sides. In August, both adults and chicks were observed feeding on the sides and tops of eskers [91]. On the Yukon-Kuskokwim Delta, Alaska, lesser sandhill cranes with recently hatched chicks concentrated activities along slough banks where vegetation, primarily sand ryegrass, was taller than the chicks and often taller than adults. Mobile family groups also used heath tundra and shortgrass meadows, where cover was less [16].

Lesser sandhill crane chick in tundra habitat, Alaska. Photo by Cal Lensink, US Fish and Wildlife Service.

Unidentified subspecies (Canadian, greater, or lesser): In the Interlake region of central Manitoba, sandhill cranes bred in a mosaic of low forested ridges interspersed with low-lying, poorly-drained forested muskegs of black spruce and tamarack, open bog and fen muskegs, and small intermittent lakes [105].

Nest sites: Forty-seven of 51 (92%) sandhill crane nests in the Interlake region of central Manitoba occurred in open fen muskegs, as did 91 of 106 (86%) observations of families with chicks, significantly more than expected based on the availability of this plant community type (P<0.01). No nests occurred in forested muskegs. While 2 nests and a few observations of chicks occurred in bog muskegs, this was much less than expected based on the prevalence of this plant community in the study area. The authors hypothesized that fens were used more than bogs because they represented more productive ecosystems and supported a more diverse plant community than bogs. Often nests were found within indentations or "bays" of muskegs. All nests were separated from upland forest by an expanse of wetland [105].

In a subset of 32 sandhill crane nests where vegetation was sampled, 17 occurred on "islands" or raised hummocks dominated by woody vegetation, and 15 occurred on herbaceous emergent vegetation. Island-hummock nests were generally at sites dominated by dwarf birch, willow, and honeysuckle (Lonicera sp.) with live or dead tamarack and black spruce. The hummock nests were usually built on moss in clumps of dwarf birch or willow and lined with pieces of sedge or bulrush. In contrast, nests in emergent vegetation were generally located at wetter sites, in stands of sedges, bulrushes, and in 2 instances, cattails [105].

Nonbreeder habitat use: Habitat use by nonbreeding sandhill cranes of migratory subspecies during the breeding season is not well studied. Nonbreeders are the most mobile social unit and are generally more nomadic and gregarious than adults [113,155]. In Wisconsin, nonbreeding greater sandhill cranes used both emergent wetlands and agricultural fields for feeding and roosting, but were found farther from wetlands than breeding cranes, and highly preferred previous years' cornfields [133]. Large groups of nonbreeding greater sandhill cranes congregated in Oregon marshes. In California, some nonbreeders were seen in the same wetlands as breeders, but some groups also used grain fields [87]. In the Interlake region of central Manitoba, flocks of nonbreeders were observed mostly in cultivated fields and wetlands along the fringes of the breeding muskeg-forest complex [105]. Similarly, in southern and central Manitoba, summer flocks of nonbreeding cranes congregated regularly in agricultural fields near the margins of boreal forest [142].

Staging and migrating habitat: Sandhill crane staging and migrating habitat consists of a mixture of ideal foraging and roosting habitat [28,31,39,51,63,70,89,100,125,148] and is in a location strategic to overall migration [51]. Midcontinental populations of sandhill cranes generally use a combination of wetland [39,51,63,70,88] and wet meadow [26,80,88] plant communities and agricultural fields [28,63,69,70,80,88,89,120] during staging and migratory stopovers. Migratory sandhill cranes also use native grasslands [28,67,69,120,128,148], river channels [26,28,39,69,115], riparian woodlands, low shrub islands [26,115], and mudflats or shallows along rivers [26,69,115].

In a landscape analysis of sandhill crane habitat use along the Platte River floodplain, staging sandhill cranes used areas with continuous grassland cover and little forest cover in close proximity to river channels. Sandhill cranes avoided areas with large contiguous patches of forest cover, small grassland areas, and small, dispersed areas with water. Areas with suitable water cover that had high levels of forest cover received limited use [125]. In Colorado, greater sandhill crane spring and fall staging areas had both abundant water and food. Large riverbottoms with small grains (primarily wheat) adjacent to water areas were used in both fall and spring, while irrigated hayfields were used only in fall [148].

Foraging: During staging and migration, sandhill cranes spend much of their time foraging in agricultural fields [28,63,69,70,80,89,120]. Native grasslands are also used for foraging [28,69,120,128]. The quality of foraging habitat is particularly important, as sandhill cranes accumulate much of the fat and nutrients needed for migration and reproduction in spring staging areas (review by [124]). It is estimated that midcontinental sandhill cranes accumulate >75% of the lipids used for migration and reproduction at spring staging areas in Nebraska [63]. Agricultural areas in close proximity to suitable roosts are preferred [31].

Sandhill cranes in southeastern Oregon [80], the Platte River Valley [28], and northwestern Indiana [89] preferred to forage in open areas offering good visibility and ease in finding food. In some cases, low vegetation height at preferred foraging areas was linked to land management practices (e.g., harvest, grazing, haying) [28,80]. In northwestern Indiana, fall activities such as harvesting, plowing, and waterfowl hunting led sandhill cranes to concentrate foraging in areas away from disturbance [89]. Fields used for foraging in southeastern Oregon ranged from 25 to 341 acres (10-138 ha) [80].

Several studies have documented the use of different plant cover types used by foraging midcontinental sandhill cranes in the Platte River Valley. Cover types used include cornfields [28,69,120], alfalfa fields [28,69,120], native grasslands [28,69,120,128], hay fields [69,128], and riverine habitats [128], though use of each cover type varies [28,69,128].

Other staging areas also receive heavy usage of agricultural fields for foraging. Greater sandhill cranes staging in southeastern Oregon foraged mostly in barley (Hordeum sp.) fields but also used oat, rye (Secale sp.), and wheat (Triticum spp.) fields, and preferred wheat when it was available [80]. Greater sandhill cranes at Grays Lake, Idaho, foraged mostly in barley fields [31]. At the Jasper-Pulaski Fish and Wildlife Area in northwestern Indiana, the largest fall flocks of midcontinental sandhill cranes foraged on corn stubble in cornfields. Spring flocks foraged in unplowed cornfields and fallow pastures [89]. Native grasslands are used as foraging habitat in some areas; meadows with perennial grasses such as beardless wildrye (Leymus triticoides), bottlebrush squirreltail (Elymus elymoides), basin wildrye (Leymus cinereus), Sandberg bluegrass (Poa secunda), and saltgrass provided foraging areas for migrating sandhill cranes in southeastern Oregon [67].

Some populations of sandhill cranes stage where agricultural crops are not available. Lesser sandhill cranes staging along the eastern Copper River Delta, Alaska, foraged in open, brush-free areas with moist to fairly dry substrates near the interface of wet meadow and medium shrub habitats. Sandhill cranes foraged in sites that contained their preferred food item, marsh arrowgrass. Other plants present included Ramenk's sedge, largeflower speargrass (Poa eminens), reedgrass, and bentgrass (Agrostis spp.). Substrates at feeding sites were almost entirely covered by moss. Lesser sandhill cranes avoided feeding at sites with high Sitka alder and willow cover, as well as excessively wet sites. The author suspected that encroaching shrubby vegetation would limit available foraging habitat in the future [51].

Roosting: Staging and migrating sandhill cranes prefer shallow water [39,51,80,88,115] and sparse vegetative cover [51,80] at roost sites. They roost in wetlands or marshes [39,63,70,88], river channels [26,28,39,69,115], mudflats or shallows along rivers [26,69,115], wet meadow grasslands [26], seasonally flooded basins [88], seasonally flooded agricultural fields [89], open fields [36], and ponds or lakes [80,134]. In the Platte River Valley of Nebraska, 57% of roosts were centrally located within foraging ranges and 37% were at the periphery [128]. Over 90% of greater sandhill cranes in Saskatchewan foraged within 5 miles (8 km) of roosts [134]. Greater sandhill cranes staging in southeastern Oregon traveled 1.4 miles (2.2 km) from roosts to feeding areas [80].

Spring and fall staging greater sandhill cranes at the Jasper-Pulaski Fish and Wildlife Area in northwestern Indiana used 3 major types of roosts: seasonally flooded basins and inland fresh meadows, inland fresh marshes with wide borders of inland fresh meadow, and inland fresh marshes bordered by trees. Near the Platte and North Platte Rivers in Nebraska, sandhill cranes roosted in a number of habitats including riparian woodlands, low-shrub islands, mudflats along the river channel, and wet meadow grasslands on adjacent river terraces [26,115].

Greater sandhill cranes staging in the fall in southeastern Oregon used small bodies of water with short vegetation for loafing. Dominant vegetation at loafing sites included broadfruit bur-reed, foxtail barley (Hordeum jubatum), beardless wildrye, and saltgrass. Mowed, flooded meadows were heavily used when available [80].

Lesser sandhill cranes staging along the eastern Copper River Delta, Alaska, roosted in medium shrub habitat, likely using the numerous large, shallow lakes with sparse sedge, sweetgale, and purple marshlocks for cover. Lesser sandhill cranes also commonly roosted on intertidal mudflats, which were largely unvegetated except for a sparse growth of macroalgae. Intertidal areas were covered by tides twice daily and consisted of open mudflats broken only by brackish sloughs draining the surrounding area. In wet meadow habitats, lesser sandhill cranes roosted in small, shallow ponds. Sandhill cranes seemed to avoid roosting in dry areas or areas with thick brush cover [51].

River channel roost characteristics: Numerous studies have examined characteristics of river channels used as roosts along the Platte River, Nebraska. Channel width is perhaps one of the most important characteristics determining suitable river channel roost habitat. In general, sandhill cranes prefer wide channels and avoid narrow channels, though definitions of wide and narrow vary by study. One study found that sandhill cranes usually roosted where unobstructed channels were at least 500 feet (150 m) wide and avoided stretches narrower than 150 feet (50 m); channel use was greatest where channels were widest [69]. Another study found that sandhill cranes used sites with channel widths of 300 to 700 feet (100-200 m) in greater proportion than their availability. Channels <300 feet (100 m) were avoided, while those >700 feet (200 m) were used in proportion to their availability [115]. A 3rd study found that sandhill cranes roosted in channels >52 feet (16 m) wide but preferred channels >157 feet (48 m) wide [39]. A 4th study found that sandhill cranes preferred channel widths >500 feet (150 m) and avoided channel widths <300 feet (100 m); channel widths at roost sites were significantly wider than at unused sites (P<0.001) [28].

Sandhill cranes avoid visual obstructions, including vegetation, islands, and riverbanks, at river channel roost sites, although one study reported that channel width was more important than visual obstruction in influencing use of river channels for roosting. When unobstructed channel width was <490 feet (150 m), most sandhill cranes roosted where vegetation was >7 feet (2 m) high [69]. Another study found that sandhill cranes roosted as close as 13 feet (4 m) to a visual obstruction, but preferred distances >82 feet (25 m) [39]. A 3rd study reported that sites 36 to 160 feet (11-50 m) from the nearest visual obstruction were used significantly more than their availability (P=0.05), while sites 0 to 13 feet (0-4 m) and >160 feet (50 m) from visual obstructions were avoided (P=0.05). Vegetated islands had little impact on the selection of roost sites, while vegetated banks had greater influence [115].

Sandhill cranes prefer shallow water at river channel roosts. One study found that water depths <8 inches (21 cm) were preferred [39]. Another study found that water depths <5 inches (13 cm) were preferred while water depths >8 inches (20 cm) were avoided [115].

Sandhill cranes may avoid some types of human development near river channel roost sites. One study found that the presence of bridges or roads adjacent to river channels reduced use by about half [69]. Another study found that sandhill cranes avoided roost sites near paved roads, gravel roads, single dwellings, and bridges, but they did not appear to avoid private roads, groups of residential buildings, gravel pits, railroads, or electrical transmission lines [115].

Wetland roost characteristics: Wetland roost characteristics vary at different staging areas. Wetland roost sites of staging and migrating midcontinental sandhill cranes in Nebraska, Saskatchewan, and Alaska were characterized as semipermanent wetlands containing shallow water and emergent aquatic vegetation [63].

At the Jasper-Pulaski Fish and Wildlife Area in northwestern Indiana, greater sandhill cranes roosted in seasonally flooded basins and inland fresh meadows. Roosting sandhill cranes did not avoid areas with woody encroachment on shorelines as long as open, shallow water was available, contrasting with river channel roosts in the Platte River Valley. Sandhill cranes also roosted among dense vegetation, which was avoided in other studies. Sandhill cranes avoided water higher than their tibiotarsal joint (about 10 inches (25 cm) high). Sandhill crane use of fall roosts was positively associated with proximity to other roosts and presence of other sandhill cranes [88].

Sandhill cranes roosting in shallow water. Photo by Wyman Meinzer

In semipermanent wetlands in the Platte River Valley, water depth, mud depth, unobstructed width, and distance to nearest shore differentiated roost and nonroost sites. Widths >39 feet (12 m) were used, with >75 feet ( 23 m) preferred, water depths ranged from 2.0 to 9.6 inches (5.0-24.4 cm), and distance to shore was as little as 3 feet (1 m), though ≥30 feet (9 m) was preferred [39].

Greater sandhill cranes staging in southeastern Oregon roosted in ponds and lakes with a mean water depth at roosting sites of 4.6 inches (11.7 cm); roosts averaged 1.4 miles (2.2 km) from feeding areas. Human disturbance did not seem to impact roost use; some roost sites were near highways or houses, but emergent vegetation blocked visibility of these features. One roost was bordered by a dike on 1 side and short saltgrass on 3 sides, which effectively blocked the view of a highway on 1 side. Roost sites varied from 1.2 to 297 acres (0.5-120 ha). Water was clear with little turbidity. Roost sites had no substantial growth of submergent vegetation [80].

Wintering habitat: Habitat of wintering migratory subspecies of sandhill cranes consists of suitable areas for foraging and roosting, usually a combination of agricultural fields or native grasslands and wetlands [32,158]. Sandhill cranes often return to the same wintering grounds every year [13]. Loyalty to wintering grounds may depend on access to agricultural croplands and pasture [13] or other local land use practices and habitat conditions [114]. The annual distribution and abundance of Canadian, greater, and lesser sandhill cranes on wintering grounds in Mexico was related to variations in food availability, wetland water levels, and disturbance [32].

Wintering midcontinental populations of sandhill cranes use wetland plant communities [3,13,32,57,61,62,100,117,141,151,158], including plant communities around lakes [61,62,158], ponds [61,158], alkali basins [61], marshes [32,151,158], mud flats [61,158], or on river bars [158]. Both agricultural fields [3,32,57,61,99,117,141,158] and native grassland plant communities [57,61,66,99,158] are commonly used. Wintering sandhill cranes use oak woodlands in Texas [57], California [54,117], Oregon, and Washington [66] and sagebrush communities in California [99].

In western Texas, lesser sandhill cranes used a variety of habitat in winter, including mixed-grass, shortgrass, and tallgrass prairies. Lakes were used for drinking water [158]. Also in western Texas, midcontinental populations of sandhill cranes wintered on shortgrass prairie invaded by mesquite and yucca, with sorghum (Sorghum sp.) and cotton fields nearby. Scattered saline, alkaline basins with permanent to semi-permanent water were present [61]. At the Bosque del Apache National Wildlife Refuge, New Mexico, sandhill cranes wintered in wetlands [141]. In California's Central Valley, flooded ricelands, pastures, and areas of native and managed marshes provided wintering habitat for Canadian, lesser, and greater sandhill cranes [117]. Some sandhill cranes winter in the western grasslands of Washington and Oregon [66].

Foraging: In winter, migratory subspecies forage in agricultural fields [3,32,57,99,141,158], wetlands or marshes [3,13,57,141], grasslands [57,99,158], open woodlands [57], and sagebrush [99].

On the Gulf Coast of Texas, sandhill cranes foraged primarily on agricultural lands but also foraged on swales dominated by rushes and gulf cordgrass (Spartina spartinae), in savanna-like areas dominated by live oak and Hercules' club (Zanathoxylum clava-herculis), and in grasslands where typical climax species included big bluestem (Andropogon gerardii), indiangrass (Sorghastrum nutans), and hairawn muhly (Muhlenbergia capillaris). A long history of livestock grazing facilitated the establishment of species such as honey mesquite (Prosopis glandulosa), live oak, and some pricklypear (Opuntia spp.) in some foraging areas. The particular habitat used for foraging depended on the availability of acorns; when acorns were not abundant, sandhill cranes were more likely to be on swales where Carolina desert-thorn (Lycium carolinianum), an alternate food item, could be found. The availability of freshwater or saltwater sources did not significantly influence habitat selection for wintering cranes in this area. Of the freshwater sources used, sandhill cranes tended to use those with <10% cover of emergent vegetation [57].

Another study on the Gulf Coast of Texas found wintering sandhill cranes feeding in palustrine and lacustrine wetlands. Foraging areas included both natural wetlands and farmed wetlands such as flooded rice fields. Sandhill cranes were also observed feeding in nonwetland fields, such as dry rice, corn, sorghum fields, and pastures. Densities were highest in wetland communities with >30% cover of shrubs, emergents, or algae [3].

Wintering lesser sandhill cranes in California foraged in grain fields, fields of short grasses, scattered sagebrush, and bare ground. Sandhill cranes avoided all shrubs in their movements while foraging [99].

Roosting: Wintering migratory sandhill cranes usually roost in or near shallow water in lakes [62,158], ponds [61,158], marshes [32,151,158], wetlands [3,62], mud flats [61,158], or on river bars [158]. Roost sites tend to be open with little vegetative cover [3,61]. Wintering sandhill cranes prefer roost sites with minimal disturbance [158].

Midcontinental sandhill cranes wintering in western Texas roosted in large lakes or alkaline basins. Water in alkaline basins never froze, providing roosting habitat throughout the winter. However, sandhill cranes did not roost in alkaline basins lacking freshwater springs. Water at basin and lake roost sites reached a maximum depth of 16 inches (40 cm). Sandhill cranes also roosted on exposed mudflats adjoining water. The availability of food, primarily sorghum stubble in this area, and freshwater were positively associated with the number of individuals at a roost. The number of individuals at roost sites also increased with the amount of surface water available [61].

Roosting of greater and lesser sandhill cranes wintering along the Cosumnes River in Sacramento County, California, occurred in valley oak forests interspersed with freshwater marshes and small stands of riparian forest. Valley oak forests contained a subcanopy of valley oak, Oregon ash, buttonwillow, and boxelder. Riparian forests were dominated by Fremont cottonwood, California sycamore (Platanus racemosa), northern California walnut, willows, and boxelder [54].

Habitat of nonmigratory subspecies: Unlike the migratory subspecies of the sandhill crane, which rely on wetlands for many of their habitat needs, nonmigratory subspecies vary in their usage of wetlands. The Florida sandhill crane shows the most similarity to migratory subspecies in its use of wetlands, while the Cuban sandhill crane completes most of its life history in dry areas.

Cuban: Cuban sandhill cranes inhabit dry savannas and pine flats year-round ([42,156], review by [124]). Most territories have sparse tree and shrub cover, are often park-like and flat, but are sometimes rocky and mountainous. Cuban sandhill crane habitat is often isolated and dry, and individuals may never encounter a marsh. Drinking water is obtained from small streams, springs, and rain pools [158].

Nest sites: In contrast to some other subspecies of sandhill cranes, Cuban sandhill cranes prefer dry, open habitat for nesting, usually placing the nest on dry, "quartz-sand" and "iron-quartz" soils. Nests may be placed in dry, grassy locations [42] or even on rocks [156]. Grasses, trees, and shrubs are sparse or dispersed in nesting areas. Nests tend to be readily visible within grasslands, although they are typically near dense vegetation that functions as a visual barrier to other pairs. In one area, these vegetational "screens" were 79 to 197 feet (24-60 m) from the nest. Most nests were small, some barely visible as the slope of the terrain increased [42].

The few nests of the Cuban sandhill crane found on the Isle of Youth were usually in dry locations, with water sometimes at a great distance. Nests had scattered tree or shrub cover and were usually constructed of pine needles. "The nest was almost on top of the mountain and surrounded by scattered tropical pines and one lone bush. Large rocks jutted through the thin soil, and on a flat rock amongst these was the nest, perfectly level except for a slightly hollow center. It was made entirely of pine needles and appeared as though the birds had whirled around and around on it, as I have observed cranes do...The nearest arroyo with water was about 300 meters from the nest" [156].

Foraging and roosting: Cuban sandhill cranes roost at night and feed by day on dry land [158].

Florida: In Georgia, Florida sandhill cranes used a mosaic of freshwater wetland types including marshes, shrub swamps, swamp forests, and lakes [78]. Populations of the Florida sandhill crane used several plant communities in north-central Florida, ranging from emergent palustrine wetlands to mesic forest. Open, upland habitat with short vegetation near permanent emergent wetland habitats was a prominent feature of territories that were occupied year-round [113]. Florida sandhill cranes avoided densely wooded areas, brackish and saltwater marshes, urban areas, and marshes with dense vegetation such as cattail or sawgrass [78].

Nest sites: Territorial Florida sandhill crane pairs in north-central Florida used pasture, wetland, and forest habitat 86.2% of the time. Pasture, emergent palustrine wetlands, and transition areas between pasture and emergent palustrine wetland were used more than expected based on availability. Densely forested habitats received only 5% of use [113].

In Florida, Florida sandhill cranes nested in small ponds and large marshes. Predominant plants in nesting ponds included sedges, bluestem (Andropogon spp.), crowngrass (Paspalum sp.), sawgrass (Cladium jamaicense), hardstem bulrush, tenangle pipewort (Eriocaulon decangulare), flattened pipewort, whitehead bogbutton (Lachnocaulon anceps), Small's yelloweyed grass (Xyris smalliana), pickerelweed, rushes, Carolina redroot (Lachnanthes caroliana), savanna iris (Iris hexagona), yellow pond-lily, dwarf sundew (Drosera brevifolia), and peelbark St. Johnswort. Many nests were placed in dense stands of pickerelweed or in clumps of peelbark St. Johnswort [158].

At the Loxahatchee National Wildlife Refuge, Florida, Florida sandhill cranes nested in wet prairie communities of relatively low stature plants interspersed with stands of sawgrass. Plant species immediately surrounding nests varied [144].

Nests of Florida sandhill cranes at the Loxahatchee National Wildlife Refuge contained a variety of plant materials, with maidencane the most frequently used plant material [144].

At the Okefenokee Swamp, Georgia, Florida sandhill crane nests were usually constructed around the perimeter of large marshes where herbaceous cover merged with stands of pondcypress and loblolly bay, or in small <1.2 acre (0.5 ha) shrub-scrub marsh openings [14]. In southern Georgia, nest sites tended to be in extensive marshy regions, often in deeper water than Florida nests. Breeding occurred in areas where sawgrass, American white waterlily, yellow pond-lily, maidencane, goldenclub, green arrow arum (Peltandra virginica), Carolina redroot, iris (Iris sp.), buttongrass, grasses, sedges and mosses provided nesting cover. Principal cover at nest sites was maidencane, bulltongue arrowhead, and sawgrass [158].

In some areas, it is clear that local populations of cranes show a preference for specific wetlands. In the Okefenokee Swamp, Georgia, Florida sandhill cranes were sighted in all large marshes, but no individuals were present in marshes <25 acres (10 ha); one region comprised only 26% of the marsh habitat but supported 65% of the local sandhill crane population [12]. In Florida, Florida sandhill cranes preferred undrained ponds 2 to 10 acres (1-4 ha) in size for nesting [158].

Foraging: Florida sandhill cranes in south-central Florida foraged primarily in pastures, native prairies, open pine flatwoods with low, scattered shrubs and dense grass-forb ground cover, and cultivated fields [76]. Florida sandhill cranes also walked into oak groves to eat acorns [158].

Roosting: Florida sandhill cranes roost at night in shallow ponds [158]. In north-central Florida, forested edges of forest-pasture transition areas were used for midday loafing during hot weather [113].

Mississippi: Mississippi sandhill cranes inhabit savanna, swamp, and pine woodland plant communities, as well as agricultural areas [126,151,161]. Ten captive-raised, juvenile Mississippi sandhill cranes selected savanna (open grasslands with scattered pondcypress and slash pine), agricultural lands, unimproved road and pond habitats in greater proportion than their availability. Bare soil, wooded drainages (bayous, swamps and creeks with pondcypress, black tupelo, and slash and longleaf pines), and woodlands (20- to 30-year-old slash pine plantations) were used less than expected based on their availability [161].

Nest sites: Mississippi sandhill cranes nest in open areas of grasses and sedges with perennial shallow water. The opening surrounding the nest is surrounded by trees and shrubs at such a distance that approaching predators are visible (review by [150]). Of 30 Mississippi sandhill crane nests in southeastern Mississippi, 22 occurred in marshy savanna swales, 5 on the edge of a swamp, and 3 in slash pine plantations. Nest sites were in sedges or grass and never hidden under a bush or small tree. Nests were made mostly from sedges and grasses (Scleria spp., Carex spp., Panicum spp., Andropogon spp.), as well as bits of sphagnum, twigs, Carolina redroot, goldencrest (Lophiola americana), and pitcher-plant (Saracenia spp.) [151]. Long-term studies show a preference for both savanna and swamp habitat for nesting (review by [150]).

Compared to other subspecies, the Mississippi sandhill crane nests in habitat with greater standing tree densities [126]. However, Mississippi sandhill cranes stop nesting in swamps that lose their open structure with the establishment of trees and shrubs [151].

Foraging: Savanna plant communities are often used for foraging [151,161], though foraging areas change through the year. During the summer, Mississippi sandhill cranes foraged in savannas, swamps, and open forest lands. During the fall, winter, and early spring, most foraged in small fields of corn and yellow nutsedge, pastures, and pecan orchards occurring within several miles of nesting territories. In the late winter and early spring, Mississippi sandhill cranes foraged, most likely for earthworms, in burned pine forests and cleared areas (review by [150]).

Roosting: Winter roosts of Mississippi sandhill cranes are usually marshes with fresh to slightly brackish water, dominated by sawgrass and black rush (Juncus roemerianus). Artificial ponds are also used, as are savannas, open forest, pastures, and moist clearings in foraging areas. During the breeding season, Mississippi sandhill cranes roost near the nest (review by [150]). Ten captive-raised, juvenile Mississippi sandhill cranes used dry roosts, primarily in savanna plant communities, for nocturnal roosting 95% of the time. Woodlands were used for daytime roosting [161].

Preferred cover: In general, sandhill cranes prefer open habitat for foraging and roosting, which allows them to see approaching predators [48,127]. Both water and vegetation may be used as protective cover, particularly at nest sites. This section summarizes information on water depth preferences and desirable plant community structure used while foraging, roosting, nesting, and hiding.

Foraging: Sandhill cranes generally forage in areas with little vegetative cover [28,51,57,78,80,89,127], which offer visibility and ease in finding food [28,80,89]. While in shrubby habitats, sandhill cranes avoid shrub cover [51,99].

Roosting: Sandhill cranes generally prefer shallow water at roost sites [3,26,39,51,69,80,88,115,155]. See roost site descriptions in Preferred habitat for details regarding water depths at roost sites.

Sandhill cranes generally use roost sites with little vegetative cover or visual obstructions [3,36,39,51,61,69,80,115], but there are exceptions. At the Jasper-Pulaski Fish and Wildlife Area in northwestern Indiana, greater sandhill cranes did not avoid areas with woody encroachment on shorelines as long as open, shallow water was available. Sandhill cranes also roosted among dense stands of vegetation, contrary to results from other studies [88]. In northwest Colorado, greater sandhill crane individuals were occasionally found roosting in trees [15]

Vegetative cover at roost sites may serve as a barrier from human disturbance. At the Jasper-Pulaski Fish and Wildlife Area, minimum distances from hunter activity averaged 460 feet (140 m) for roosts surrounded by woods, and 1,250 feet (380 m) for roosts visible from roads [88]. In southeastern Oregon, staging sandhill cranes commonly roosted near highways or houses, but emergent vegetation blocked visibility of these features [80].

Nesting: Sandhill crane nests are often built in shallow, standing water, though some populations of the Cuban, lesser, and Mississippi subspecies tend to nest on dry land (review by [124]). Water depth may influence nest size, with wetter sites necessitating higher, larger nests [16,31,135]. Standing water around a nest may offer protection from terrestrial predators [4,8,101]. Because sandhill cranes inhabit areas in a wide range of habitats, it is likely that a preference for specific water depths at nest sites relates to local site conditions. Documented water depths at nests range from 0 to 12 inches (0-30 cm) (see [4,6,21,25,31,82,101,104,127,144,151,158,159] for more information) and may change over the course of the breeding season [151] or vary by habitat type in the same area. At Grays Lake, Idaho, average water depths at nest sites ranged from 5 to 7 inches (12-18 cm) over 4 years, varying from 2 inches (4 cm) in wet meadows to 17 inches (43 cm) in cattail-bulrush habitats [4].

While some authors suggest that sandhill cranes avoid deep water [31,45,127], other studies have shown that some subspecies or populations may prefer nest sites with water depths greater than what is generally available. In both Idaho [4,101] and southeast Oregon [64,65] mean water depth was higher at successful greater sandhill crane nests compared to unsuccessful nests. At the Mississippi Sandhill Crane National Wildlife Refuge, nests typically had more standing water than the average available habitat during both territory selection and nesting [126]. In eastern Siberia, water depth was significantly higher at 3 lesser sandhill crane nest sites than at random sites (P=0.018) [159].

A preference for vegetative cover at sandhill crane nest sites is not consistent; the Cuban and the Mississippi subspecies prefer open sites for nesting, while other subspecies may nest in areas with either high or low vegetative cover. Preference for vegetative cover at nesting sites may relate to local conditions such as the presence of water, the availability of vegetative cover, and predation pressure. Vegetative cover at nest sites may provide isolation from predators [64,65,82,83,86,126], other sandhill cranes ([12,105,126], review by [150]) and human disturbances [15,58,126]. Vegetative cover or other visual barriers such as topography may facilitate higher densities of nesting sandhill cranes ([12,105], review by [150]). Dense vegetation also provides material for nest building [8]. Some authors explain that sparse vegetation found at nest sites may be due to the removal of surrounding vegetation in nest construction [9,126,127,151].

Vegetative cover at nest sites is summarized below for 5 of the sandhill crane subspecies, as well as from one population of an unknown subspecies in Saskatchewan.

Cuban sandhill crane: Cuban sandhill cranes preferred dry, open habitat for nesting, with sparse or dispersed grasses, trees, and shrubs in the nesting area [42,156]. Nests tended to be readily visible within grasslands, although they were typically near dense vegetation that functioned as a visual barrier to other pairs. These vegetational "screens" were usually 79 to 197 feet (24-60 m) from the nest [42].

Florida sandhill crane: Florida sandhill crane nests may be placed in areas with either high or low vegetative cover. In the Okefenokee Swamp, Georgia, Florida sandhill crane density was highly correlated with the volume of herbaceous cover within individual marshes (r = 0.93, P<0.001); marshes with low crane density had <5% coverage by herbaceous vegetation [12]. Florida sandhill crane nests in Florida were found both along densely vegetated ponds [76] and marshes; many marsh and pond nests in Florida were placed in dense stands of pickerelweed or in clumps of peelbark St. Johnswort [158].

Conversely, at Loxahatchee National Wildlife Refuge, Florida, vegetation was sparse or absent at 65% of Florida sandhill crane nest sites. The remaining 35% of nests were in fairly dense stands of maidencane or pickerelweed, though cover was never taller than 12.0 to 18.0 inches (30.5 to 45.7 cm). Nests in denser vegetation tended to have "marker" vegetation nearby, either a shrub or dead snag [144].

Greater sandhill crane: Greater sandhill crane nests may be placed in areas with either high or low vegetative cover. One greater sandhill crane nest in central Wisconsin was concealed on 2 sides by clumps of 4-foot (1 m) willows, while the other 2 sides permitted unobstructed vision across the 300 to 400 acre (121-162 ha) sedge meadow [45]. In Maine, a single nest was located in cattail cover that was so dense that the nest was not viewable without flushing the incubating parent [104].

Most nests of the greater sandhill crane at Grays Lake, Idaho, were conspicuously located in open areas, as most were constructed prior to new vegetative growth. A few nests were located in the dense cover of bulrush and cattails [31]. A later study at Grays Lake, Idaho, found that vegetation height at nests varied across the nesting season and among years. The majority of nests (56.8%) occurred in plant communities where vegetation was <1.6 feet (0.5 m) tall [4], and 58% of nests were surrounded by relatively short vegetation <12 inches (30 cm) tall [9]. Vegetation height was not useful for predicting nest success [4]. In eastern Idaho, 23% of nests were in vegetation <12 inches (30 cm) tall, 61% of nests were in vegetation 12 to 24 inches (30-60 cm) tall, and 16% of nests were in vegetation >24 inches (60 cm) tall [101]. Two greater sandhill crane nests in Yellowstone National Park, Wyoming, were located in a "dense" cover of rushes [25]. The nests of greater sandhill cranes in northwest Colorado were surrounded by dense cover, usually willow [15].

In the Shasta Valley of California, greater sandhill cranes seemed to prefer tall marsh vegetation, such as bulrush or cattails, at nesting sites [127]. In northeastern California, most greater sandhill crane nests were in open wet meadows. The height of vegetation surrounding nests averaged 11.7 inches (29.6 cm). Forty-five (80%) nests were visible at distances >245 feet (75 m), 10 (18%) were visible at 30 to 245 feet (10-75 m), and 1 (2%) was visible at <30 feet (10 m) [82].

Lesser sandhill crane: Lesser sandhill crane nests may be placed in areas with either high or low vegetative cover. Visibility from one lesser sandhill crane nest in Alaska was nearly a mile in all directions and other nests in the area were situated on top of poorly vegetated sandy knolls, with good visibility. In contrast, one nest was surrounded by hip-high dead rushes, grasses, and sedges [158].

In eastern Siberia, 3 lesser sandhill crane nests were found in areas where vegetation height was significantly higher at nest sites than random sites (P <0.001). Mean vegetation height was 7.92 inches (20.12 cm) and mean vegetation cover was 76.28%. However, because most vegetation was under snow at the time of nest construction, the author hypothesized that characteristics of tundra polygon formation might have had more impact in determining safe nesting sites than vegetative cover in this habitat [159].

Mississippi sandhill crane: Mississippi sandhill cranes nest in open areas. One review suggests that Mississippi sandhill cranes prefer sparse cover at nest sites so that they can see approaching predators [150]. Five nests at the Mississippi Sandhill Crane National Wildlife Refuge had lower cover of herbaceous vegetation at nest sites compared to reference areas (P=0.006) [126]. Nests were located in sedges or grasses and were never hidden under bushes or small trees, though bushes and small trees could be within 12 inches (30 cm) of the nest. Previously open swamps that were overgrown with trees and shrubs were no longer used for nesting [151].

Unknown subspecies (Canadian, greater, or lesser): Tall emergent vegetation was considered important protective cover at sandhill crane nests in southeastern Saskatchewan; visual obstruction from nests averaged 27 inches (68 cm) at 3 feet (1 m) from nests, 19 inches (49 cm) at 16 feet (5 m), 22 inches (56 cm) at 33 feet (10 m), and 20 inches (51 cm) at 66 feet (20 m) [21].

Hiding cover for young: Vegetation may be used as hiding cover for young sandhill cranes. Lesser sandhill cranes with recently hatched chicks concentrated activities along slough banks where vegetation, primarily sand ryegrass, was taller than the chicks and often taller than adults. Once family groups became mobile, families also used heath tundra and shortgrass meadows with less cover [16]. Observations of greater sandhill crane chicks and adults in Michigan were generally difficult due to their low visibility in tall marsh vegetation. In one situation, when approached by researchers, chicks hid in sedge cover while the parents circled overhead [155].

Young sandhill crane in vegetation. Photo courtesy of US Fish and Wildlife Service.

Use of burned areas: Sandhill cranes use postfire habitat, particularly for foraging ([48,57,93,120,131,143,158,160], Reinecke personal communication cited in [69]). See Indirect fire effects for more information on sandhill crane use of burned areas.

FOOD HABITS:
Sandhill cranes are omnivorous, and their diets vary widely depending on season and location. Diets usually include a mixture of agricultural crops, plant tubers, seeds, berries, invertebrates, and other animal matter, the proportions of which may vary seasonally [45,51,89,91,158,159] or by habitat [120,158].

Agricultural grains may be an important component of the diet, though sandhill cranes successfully breed in areas with few or no agricultural fields [16,91,158,159]. Major sandhill crane congregation, particularly during staging and migration, occurs in regions where agricultural grains are widely available. Sandhill cranes staging in the spring along the Platte River in Nebraska foraged in corn fields, alfalfa fields, and native grasslands. Diet varied by foraging habitat; sandhill cranes foraging in cornfields consumed >99% corn, while those in alfalfa fields and native grasslands consumed 79% to 99% invertebrates (beetles, snails, crickets, grasshoppers, cutworms). The overall diet across all habitats was 97% corn and 3% invertebrates [120]. Crop consumption may negatively impact local agricultural producers, presenting a management challenge in areas of dense sandhill crane concentrations (See Management considerations).

Along with agricultural crops, sandhill cranes consume other vegetation. Wintering greater sandhill cranes at the Bosque del Apache National Wildlife Refuge, New Mexico, consumed rhizomes of the nonnative weeds Johnson grass and field bindweed (Convolvulus arvensis) [141]. Native vegetation is also widely consumed:

Insects (Hexapoda) and other invertebrates may comprise a large proportion of sandhill crane diets [69,158], particularly in areas with few agricultural crops, like parts of Florida or Cuba. Insects and other invertebrates were likely more important food sources prior to agricultural crop availability [158]. Invertebrates are consumed in all seasons, including breeding [16,104,159], fall [45,51] and spring staging [51,69,89,120], and overwintering [56,57]. Earthworms (Oligochaeta) [69,155,158] and grasshoppers (Caelifera) [155,158] may be particularly important food items in some areas, though many different invertebrates are consumed; wintering sandhill cranes in Texas consumed adult and larval beetles (Coleoptera), crickets (Ensifera), grasshoppers, moths (Lepidoptera), and snails (Gastropoda) [10]. Invertebrates made up <5% of the diet of wintering sandhill cranes in Texas [10,120].

A range of other food items may be consumed based on location and opportunity. These include amphibians (Amphibia) [104,158], reptiles (Reptilia) [99,104,158], fish (Pisces) [159], crayfish (Parastacidae) [158], snails [104,158], small mammals [104] such as mice (Muridae) [158], lemmings (Lemmus, Synaptomys, Dicrostonyx spp.) [41,91,158,159], and voles (Myodes spp.) [16,51,159], small fish [16], bird (Aves) eggs [104,158,159], and nesting birds such as willow ptarmigan (Lagopus lagopus), snow geese (Chen caerulescens) [158], Lapland longspurs (Calcarius lapponicus), shorebirds [159], and ducks (Anatidae) [79]. Adult lesser sandhill cranes in the Northwest Territories were observed scavenging meat scraps (mostly young snow geese) from the den of an arctic fox (Vulpes lagopus). Lesser sandhill cranes were also observed scavenging from sites where fishermen left waste [91]. Sandhill cranes scavenged caribou (Rangifer tarandus) carcasses in the Northwest Territories [41].

MORTALITY:
Predation: Eggs and chicks are vulnerable to terrestrial predators such as the coyote (Canis latrans) [82,83,84,87,100,127,161], northern raccoon (Procyon lotor) [14,35,82,100,127,158], northern river otter (Lutra canadensis), bobcat (Lynx rufus) ([14,35,161], review by [150]), American black bear (Ursus americanus) [14], grizzly bear (U. arctos horribilis), arctic fox [159], skunk (Mephitidae) [100], mongoose (Herpestes auropunctatus) [42], domestic dog (Canis familiaris) ([42,161], review by [150]), domestic cat (Felis catus), feral pig (Sus scrofa) [35,42], and American alligator (Alligator mississippiensis) [14,35,144]. Avian predators include the common raven (Corvus corax) [83,84,87,100,127], American crow (C. brachyrhynchos) [100,155], fish crow (C. ossifragus) [35], red-tailed hawk (Buteo jamaicensis) [35,155], Cooper's hawk (Accipiter cooperii) [155], northern harrier (Circus cyaneus) [43,155], and great horned owl (Bubo virginianus) [35,155]. Predation rates on eggs and chicks may be lower in years when alternative prey (e.g., small mammals) is abundant [16].

The mobility of adults makes predation more difficult. Golden eagles (Aquila chrysaetos) and coyotes killed greater sandhill cranes staging in southeastern Oregon [80]. Bald eagles (Haliaeetus leucocephalus) pursued and killed adult lesser sandhill cranes staging on the Copper River Delta, Alaska [51].

Predator control programs: Population dynamics of predators, including fluctuations resulting from predator control programs, may influence sandhill crane populations [83]. Predator control programs over 19 years at the Malheur National Wildlife Refuge, Oregon, positively impacted sandhill crane populations; nests made in years with predator control had greater nesting success (P<0.01), lower mortality rates of young (P<0.01) [85], higher fledging success (P<0.05) [81], and higher annual recruitment rates (P<0.025) [85]. Later studies in the same location did not find that predator control influenced nest success. However, other land management practices, specifically prescribed burning, may have reduced the abundance of small mammal prey for predators, thus increasing pressure on sandhill cranes [65]. See Indirect fire effects for more information on this study.

Other sources of mortality: Sandhill cranes are hunted in some parts of their range ([16,32,33,37,78,106,138], review by [124]) (See Hunting for more information). Nonhunting mortality of adult sandhill cranes results from collisions with power lines ([31,34,88], review by [150]) or illegal shooting ([31,161],review by [150]). Two juvenile Mississippi sandhill cranes were struck by vehicles on a highway [161]. Large, concentrated flocks may increase the risk of disease [61], including outbreaks of avian cholera and botulism. Sandhill cranes may also die due to poisoning from moldy corn, waste peanuts, and lead [162]. Extreme weather events, including lightning and hailstorms, have also killed sandhill cranes [162]. Flooding due to heavy rainfall often destroy eggs and kill chicks (review by [150]).

Trampling of juvenile sandhill cranes by cattle has been documented [31], and the reaction of adult sandhill cranes to large mammals suggests that trampling by large mammals is a concern. A pair of sandhill cranes made bodily contact with a foraging young bull moose in western Wyoming, forcing it to alter its course away from a chick concealed in riparian meadow vegetation. A young cow moose similarly suffered a wingblow to the face after ignoring warning cries and approaching parents. Older bull moose and females with calves have been observed moving away from vocalizing sandhill cranes, suggesting an avoidance learned with age [1]. In eastern Siberia, lesser sandhill cranes chased or charged arctic foxes and caribou that approached their nest [159].

MANAGEMENT CONSIDERATIONS:
Sandhill cranes present many management challenges. They occur in a wide variety of habitats that span both public and private land, and migratory subspecies require adequate habitats across a vast geographical range. Management considerations therefore vary by region and associated vegetation types. This discussion is not meant to address all aspects of sandhill crane management. See the following references for detailed reviews of sandhill crane management considerations: [102,124,132,150]. For information on fire and sandhill crane management, see Fire management considerations.

Population trends: The life history characteristics of sandhill cranes, particularly delayed maturity, long-term monogamy, annual breeding, small clutch size, and extensive pre- and post-natal parental care, result in naturally low recruitment that limits the species' ability to recover from declines [65]. Major sandhill crane population declines in the past occurred largely due to activities associated with human population expansion, including marsh drainage, increased human presence, human development of breeding areas [31], and conversion of native plant communities to agriculture [49]. As of 1996, sandhill crane populations were estimated to contain at least 520,000 individuals and to be generally stable to increasing (review by [102]). However, local extirpations or population declines remain an issue [52], and the Cuban and Mississippi sandhill cranes are currently listed as endangered subspecies [149].

A loss of habitat in some areas, like staging grounds in the Platte River Valley, has concentrated sandhill crane populations to a greater extent than historical gatherings. Such population concentration may lead to increased prevalence of disease or lethal exposure to local, unpredictable events such as oil spills, hailstorms, pesticide exposure, or contamination of grains. Concentrations may also increase the probability that historically distinct subspecies would interbreed, since pair bonding may occur at staging areas (review by [124]).

Habitat management: Habitat management for sandhill cranes addresses a variety of issues, including wetland conservation, vegetation change, private land use, grazing, and timber production.

Wetland conservation: For most sandhill crane subspecies, wetland habitat is used in all aspects of life history. Wetlands in many areas may be at risk due to conversion to agriculture [38,63,137,160], wetland drainage ([35,151], reviews by [124,150]), human development ([56,78,148,151], review by [124]), and demand for water elsewhere [28,63,69]. For example, diversion of water along the Platte River altered sandbar morphology [28,63,69] and sandbar vegetation [26], rendering some areas unsuitable for roosting. Some sources believe that wetland preservation and enhancement are the most important issues in sandhill crane conservation ([4,28,52,63,65,69,87], reviews by [29,124,150]). In some breeding areas, water levels can be managed to optimize availability of suitable nesting habitat and increase nest success [4]. In wintering areas, water levels can be managed to provide adequate drinking water and prevent high levels of agonistic behavior in wintering populations [137].

An increase in vegetative cover may not be detrimental to sandhill cranes in all situations. One study in Wisconsin suggested that brush establishing in formerly open areas may facilitate sandhill crane nesting along small marshes on private lands, because it provides a barrier between the nest and human disturbance [58].

Private land use: While sandhill cranes use public lands with specific management guidelines to meet their habitat needs, they also rely on private lands [78] for breeding [84,87,127], roosting [88], and foraging [69,160]. Though many private landowners manage property for wildlife enhancement, in other cases sandhill cranes experience habitat loss due to development of private lands ([151], review by [124]). This issue is of particular concern in areas where resident subspecies have relatively limited potential habitat, as in Florida, Georgia, and Mississippi [78,150,151].

Grazing: Grazing is a common practice in many areas where sandhill cranes occur. The impact of grazing on sandhill cranes is variable. In some areas grazing, alone or combined with other techniques, is used to create the open vegetative structure preferred by foraging sandhill cranes [120,127,132]. In contrast, a long history of grazing at the Aransas National Wildlife Refuge facilitated the establishment of shrubby species, including mesquite and live oak. Less than 6% of all sandhill crane sightings occurred on grazed pastures with shrub encroachment [57]. At the Hart Mountain National Antelope Refuge in southeastern Oregon, sandhill cranes were not found in areas with livestock grazing; vegetation of grazed areas was sparse, had little sedge cover, and supported dense shrubs, including sagebrush and rabbitbrush (Chrysothamnus spp.). Instead, sandhill cranes were detected in riparian areas where livestock had been excluded for more than 40 years [30]. At the Aransas National Wildlife Refuge on the Gulf Coast of Texas, livestock trails may have provided wintering sandhill cranes access to acorns in some dense shrub thickets. However, sandhill cranes rarely used pastures that experienced winter fire and summer grazing, instead favoring pastures that only experienced winter fire [57]. See Indirect fire effects for more information on this study.

Livestock grazing may have a negative impact on nesting sandhill cranes. Spring grazing by livestock that reduced cover around nests was identified as a "significant" factor in the decline of the greater sandhill crane in Oregon and California (review by [23]). In northwestern Colorado, disturbance from grazing led 1 pair to abandon their nesting territory [15]. In southeastern Oregon, greater sandhill crane nests were examined in "idle", grazed, and hayed wetlands. Predation rates were higher in grazed than in idle habitat because cattle trails provided easy access for predators. Cattle also bedded in emergent vegetation, reducing concealment cover for nests. The authors also hypothesized that the reduction in vegetative cover resulting from grazing and mowing may have caused a decline in small mammal prey, increasing the predation pressure on sandhill cranes [86]. Juvenile sandhill cranes have been trampled by cattle [31].

Grazing had no impact on greater sandhill crane nest success at Grays Lake, Idaho [4] or Malheur National Wildlife Refuge in southeastern Oregon [65].

Timber production: Management of forests for timber may have positive or negative effects on sandhill crane habitat. In Wisconsin, timber harvest in tamarack swamps created a more open forest structure, and associated burning in peatlands created deeper and more permanent marsh habitat, both of which benefited breeding sandhill cranes [58]. In Mississippi, timber production often involved swamp drainage, prompting a shift in local plant communities from open meadows to "dense brushy jungles" unsuitable for Mississippi sandhill crane nesting [151].

Hunting: Sandhill cranes are killed by subsistence hunters in both Alaska [37] and Mexico [32]. Sport hunting is allowed in some parts of Canada and the United States, though the lack of information regarding the impacts of hunting has caused some concern ([16,33,78,106,138], review by [124]), particularly due to the fact that sandhill cranes have the lowest recruitment rate of any bird species hunted in North America [33]. Other concerns regarding hunting include the sandhill crane's late breeding age, the greater likelihood of juveniles to be harvested, and the concern that hunters could confuse sandhill and whooping cranes (review by [124]).

Besides causing direct mortality, hunting may stress sandhill cranes by flushing them from roosting and foraging areas during staging or migration. In North Dakota, sandhill cranes exposed to hunting pressure appeared more wary and easily flushed, made more movements during the day, and spent more time in the air than before the hunting season began. Some individuals moved to areas where hunting pressure was less or absent. Case studies of individual radio-tagged birds showed that one sandhill crane and its family moved to 7 different locations over 17 miles (27 km in one day in response to disturbance from hunters; this family spent most of the day in the air and not foraging or loafing. Disturbance by hunters influenced sandhill crane movement locally but did not cause them to accelerate their migration, though that result has been observed in other studies [106]. At the Jasper-Pulaski Fish and Wildlife Area in northwestern Indiana, disturbance by waterfowl hunters reduced roost use by greater sandhill cranes. Sandhill cranes avoided human disturbance by maximizing their distance and visual isolation from hunter activity, though this distance varied with vegetative cover; minimum distance from human activity averaged 460 feet (140 m) for roosts surrounded by woods and 1,250 feet (380 m) for roosts visible from roads [88]. Sandhill cranes also shifted foraging locations in response to hunting disturbance [89].

Crop depredation: Crop depredation is a concern in many areas; sandhill cranes have been eating crops at least since Europeans settled North America. Individual sandhill cranes wintering in western Texas removed as much as 1 lb (470 g) of sorghum/day [62]. At spring staging areas, daily rates of lesser sandhill crane weight gain and fat deposition averaged 0.6 to 0.8 ounces (18-25 g) for males and 0.5 to 0.6 ounces (13 -16 g) for females [70]. The consumption of grains often prompts illegal shooting ([78,151], review by 115), and legislation in some states allows hunting or management of sandhill cranes in response to crop depredation (review by [124]). In some areas, sandhill cranes may compete with large flocks of other bird species, including the Canada goose and lesser snow goose, for agricultural grains [28]. One management action to mitigate crop depredation is to plant crops on public lands specifically for the use of sandhill cranes, particularly in areas of population concentrations like staging and wintering grounds (review by [150]).

Human disturbance: Sandhill cranes may be sensitive to human disturbance, particularly at nest sites ([38,148], review by [150]). On numerous occasions, disturbance by researchers has led sandhill cranes to abandon or destroy nests [9,31,35,65,151,158]. In the Green Swamp of Florida, Florida sandhill cranes habituated to human disturbance, with some pairs nesting within 1,300 feet (400 m) of highways, railroads, and mines. Some pairs were also tolerant of helicopter flyovers, citrus harvesting and grove maintenance, a cypress mulching operation, and heavy local truck traffic [35]. Population levels may influence sandhill crane tolerance of human disturbance; in a greater sandhill crane population in Michigan that increased over 12 years of study, the average wetland used for nesting became smaller, shallower, and closer to human disturbance each year [53].

While roosting along the Platte River, Nebraska, sandhill cranes avoided roost sites near paved roads, gravel roads, single dwellings, and bridges but they did not appear to avoid private roads, groups of residential buildings, gravel pits, railroads, or electrical transmission lines [115]. It has been suggested that human disturbance may be mitigated by the presence of vegetative cover as a barrier at nesting [58] and roosting sites [80,88].

See Fire management considerations for information on the impact of prescribed fire-related human disturbance on sandhill cranes.

Endangered species considerations: There is no published information on recovery efforts for the endangered Cuban sandhill crane. Recovery efforts for the Mississippi sandhill crane include the captive rearing of Mississippi sandhill cranes beginning in 1965 and the establishment of the Mississippi Sandhill Crane National Wildlife Refuge in 1975. Captive individuals were first released in 1981 to supplement a population estimated at 50 to 60 individuals. Scientists estimate a population of 160 may be needed to sustain the nesting population, with efforts to increase and stabilize the population costing $2.5 million over 3 years as of 1991. However, the suitable habitat available may only support 30 to 34 nesting pairs, with additional habitat limited due to the development of pine plantations, exclusion of fire, and the draining of savannas. Low genetic diversity of the population is also a concern (review by [150]).

Sandhill cranes may play a role in recovery efforts for the federally endangered whooping crane. Sandhill cranes in Idaho have accepted and hatched whooping crane eggs, have reared and cross-fostered whooping crane chicks as their own, and have remained with the young through their first fall migration, winter, and for at least a portion of spring migration [105].

FIRE EFFECTS AND MANAGEMENT

• DIRECT FIRE EFFECTS
• INDIRECT FIRE EFFECTS
• FIRE REGIMES
• FIRE MANAGEMENT CONSIDERATIONS

DIRECT FIRE EFFECTS:
Fire during the breeding season has the potential to destroy sandhill crane nests and eggs and kill chicks [48]. In southern Michigan, a "severe" fire set by farmers in early May of 1942 destroyed at least one greater sandhill crane nest when the fire jumped a creek and burned in forested areas [155]. In Wisconsin, American woodcock and mallard nests were destroyed by an April prescribed fire in marsh and wetland habitat, which led the author to hypothesize that sandhill crane nests in the area could also be destroyed [154].

Prescribed fire conducted in the nonbreeding season, when chicks are mobile, should have little direct impact on sandhill cranes. However, captive-reared juvenile Mississippi sandhill cranes kept in holding pens may be limited in their ability to avoid the direct impacts of fire and associated equipment due to flight restraints. Nevertheless, in many years of prescribed fires, no direct juvenile or adult mortality from fire has been observed at the Mississippi Sandhill Crane National Wildlife Refuge [48].

Fire may cause local populations of sandhill cranes to relocate temporarily. At the Mississippi Sandhill Crane National Wildlife Refuge, Mississippi sandhill cranes typically flew away as flames from prescribed fires advanced or the equipment or personnel involved approached. Family groups were sometimes herded out of burn units prior to burning but returned to breeding territories by the next morning [48]. During the "great fire" of April 1932, Florida sandhill cranes were temporarily forced east and out of the Okefenokee Swamp. This was the only time the local population left the swamp [47].

INDIRECT FIRE EFFECTS:
Fire may have both positive and negative indirect effects on sandhill cranes. Fire may restore historically open stand conditions in many parts of the sandhill crane's range where fire exclusion has led to vegetative encroachment (See Fire regimes). In this way, fire may improve roosting and foraging habitat as well as food availability for sandhill cranes. In contrast, a loss of vegetative cover, particularly in nesting areas, may limit nest construction or make nests vulnerable to predation. See Preferred cover.

Foraging: Numerous studies have documented sandhill cranes foraging in burned areas, in some cases, immediately after fire ([48,57,93,120,131,143,158,160], Reinecke personal communication cited in [69]).

Fire may create the open habitat ideal for foraging sandhill cranes [93,96,120,143], and may increase the availability of favored food items including some plants [12,27,48,64,65,143], earthworms ([120,131] Reinecke personal communication cited in [69]), and insects [48,64,65,158]. One study suggests that fires may improve foraging potential as soils in burned sites tend to thaw earlier than in unburned sites, facilitating early availability of invertebrates and high protein vegetation [64,65]. In the Okefenokee swamp in Georgia, Florida sandhill cranes "often feed on fresh burns apparently picking up scorched insects, lizards, etc." [158]. At the Mississippi Sandhill Crane National Wildlife Refuge, Mississippi sandhill cranes fly into burned areas immediately after fire to forage, presumably for easily observable insects. They also pull up new vegetative shoots emerging within a week after fire [48].

Sandhill cranes in a recently burned area at the Mississippi Sandhill Crane National Wildlife Refuge. Photo courtesy of US Fish and Wildlife Service.

The following studies document sandhill cranes foraging in postfire habitat resulting from both wildfire and prescribed fire. This section discusses fire effects on foraging habitat during breeding, wintering, and spring staging.

Breeding: The one study reporting sandhill cranes foraging in burned areas in the breeding season suggests that both spring and fall fires may improve foraging habitat, though this improvement may last only a few years. The U.S. Forest Service conducted 2 prescribed fires in 1974 in a sagebrush community in northwestern Wyoming. The spring fire was conducted in June across 37 to 49 acres (15-20 ha). Spring moisture and low and discontinuous fine fuel loads resulted in a patchy fire of varying severity, ranging from complete consumption of vegetation in some areas, to partial consumption, to no consumption. The fall fire was conducted in August across 173 to 198 acres (70-80 ha). Due to a high fine fuel load, all "living and dead vegetation was consumed", resulting in large areas of bare ground covered with ash [95]. Both spring and fall fires reduced forb cover, but forbs recovered to prefire levels within 2 growing seasons. Grass cover declined and had not recovered after 2 growing seasons. Both fires resulted in open areas which nonbreeding birds used for hunting and foraging. Greater sandhill cranes, presumably breeding in the vicinity, foraged in the burned area after both fires; they were considered rare (< 5 sightings) both before and after the spring fire, and were not present before but abundant (>5 sightings) after the fall fire [93]. They used the unburned control area minimally in only 1 year of surveys.

Wintering: Three studies from the southern United States indicate that both wildfire and prescribed fire provide foraging opportunities for wintering sandhill cranes. The Okefenokee Swamp experienced several fires during an extended drought in 1954 and 1955. Fires from July 1954 to June 1955 were started by both lightning and people. Approximately 329,600 acres (133,400 ha) (80%) of the peat swamp burned, as did 140,000 acres (57,000 ha) of the surrounding pine forests. Most of the area experienced moderate- or low-severity fire, though some areas experienced high-severity fire. There was no evidence to suggest that fires were detrimental to sandhill cranes; instead, postfire conditions seemed to "favor" sandhill cranes. Counts made before and after the drought indicated that the resident population of Florida sandhill cranes was stable before and after the drought and fires, and that the winter population was much greater after fires. An increase in Carolina redroot after fire, a favorite food of sandhill cranes, may have been the cause of the increase in wintering sandhill cranes, though inclement weather in other parts of Florida may have also contributed to the local increase [27].

At Paynes Prairie in northern Florida, the Florida Department of Natural Resources implemented a prescribed fire program with a 3-year rotation. In 2 different years, wintering greater sandhill cranes shifted their foraging from adjacent private lands to sections of Paynes Prairie that had been burned the previous fall (October or November). In one year, sandhill crane use of the burned area increased from 300 individuals just prior to the fire, to 1,500 individuals "immediately" after the fire. Greater sandhill crane population estimates at Paynes Prairie were highest the winter immediately following fire [160].

At the Aransas National Wildlife Refuge on the Gulf Coast of Texas, a series of treatments, including winter prescribed fire and winter fire-summer grazing combinations, was conducted over 3 years to reduce shrub encroachment in tallgrass prairie interspersed with wetlands. Plot size ranged from 519 to 2,095 acres (210-848 ha). Head fires were used in combination with backing and flanking fires in November (for burn-grazed plots) and February and March (for burn-only plots) in all plots annually for 3 years. Winds ranged from 10 to 18 miles/hr (16-29 km/hr) at the time of burning; temperatures ranged from 64.0 to 72.0 °F (17.8-22.2 °C). Over the 3 years, fire characteristics were variable depending on local moisture conditions and fuel loads. Fires were characterized as "very hot", "patchy", "complete", or "poor". Prescribed burning of upland habitats reduced grass, forb, and oak shrub cover, and increased the openness of the habitat. After burning, vegetative cover <24 inches (60 cm) tall recovered to prefire levels after 1 or 2 years in the presence of livestock grazing. Shrubs and trees >24 inches (60 cm) tall were little affected by winter burning. Oak stem density increased following burning, but returned to prefire densities after 2 or more years. Acorn production was eliminated for 1 year after burning, but production resumed after 2 or more years. Grazing slowed the recovery of grasses and forbs following fire but had no measurable effect on oak stem density, oak stem height, acorn density, or visibility. Carolina desert-thorn fruits were fewer in some grazed areas compared to ungrazed controls in some years. Fewer insects were present in burned-grazed pastures compared to burned-only or control pastures. Burn-grazed pastures were only used by sandhill cranes in 1 winter when acorn densities were very high. Most use of pastures by sandhill cranes occurred in recently burned grassland, with more than 92% of sandhill crane observations made on pasture burned within the previous month. Within recently burned pasture, sandhill crane use was centered on shrub habitat, where acorns were exposed by fire. Stomach contents also contained burned insects [57].

Spring staging: In spring staging areas, sandhill crane foraging in areas burned by prescribed fire varies; some burned areas attract foraging sandhill cranes, while sandhill crane use of other burned areas changes minimally.

At the Lillian Annette Rowe Sanctuary along the Platte River, Nebraska, managers implemented a grassland management plan that combined fall haying and spring and fall prescribed fire, with the goal of improving foraging habitat for staging cranes by increasing invertebrate populations, reducing vegetative height, and controlling woody and nonnative species. Early spring burning improved availability of invertebrates; an April fire immediately attracted sandhill cranes to feed on earthworms. It also reduced the height of prairie vegetation prior to sandhill crane arrival, improving foraging habitat by creating preferred areas of low vegetation. After sandhill cranes departed, burning in May controlled encroaching woody and nonnative vegetation such as cool-season grasses. Across the landscape, the area was managed so that migratory sandhill cranes would always have access to at least one area that had been burned in early spring, late spring, or fall, or had been hayed [131].

In staging areas in central Nebraska, sandhill cranes foraged in native grasslands within weeks after an early spring prescribed fire. The sandhill cranes fed primarily on earthworms which were abundant in the upper soil strata. Ungrazed, unburned native grasslands were otherwise avoided (Reinecke personal communication cited in [69]). Also in Nebraska, sandhill cranes "responded immediately" to an experimental prescribed fire set in a stand of big bluestem, switchgrass panicum, and yellow Indiangrass during April 1978. Two individuals collected at the site had eaten earthworms. The authors hypothesized that spring burning promoted earthworm activity by increasing solar radiation, soil temperature, and the quantity and quality of soil organic matter [120].

In wetlands of the Rainwater Basin region in south-central Nebraska, several prescribed burns were conducted between mid-March and early May from 2002 to 2004. Wind speeds ranged from 5 to 20 km/hour. All burned wetlands contained water, and most were burned to the water's edge, though in a few cases, a narrow perimeter of vegetation was left along the water's edge. Burned wetlands ranged from 16 to 640 acres (6.5-259 ha). Bird species were surveyed 7 days before and 7 days after fire. Sandhill cranes were detected both before and after fire, but at very low frequency. They were not detected in unburned reference wetlands [18].

Nesting: Indirect fire effects on sandhill crane nesting may be positive or negative depending on fire effects on vegetative cover, nesting materials, and predation potential. There is some concern that spring fire may consume nesting material, consequently limiting nest construction [4,48,64,65,151]. However, sandhill cranes have been documented nesting in burned areas in both Mississippi [48] and southeastern Oregon, where 3 greater sandhill crane nests were found in a burned wetland [86]. Fire may stimulate the growth of potential nest cover plants. At the Mississippi Sandhill Crane National Wildlife Refuge, growing-season prescribed fire prompted the growth of native bunchgrasses, which managers suspected would provide cover for nesting Mississippi sandhill cranes [48].

Sandhill crane family groups may use burned areas; one family group was observed in a burned upland forest site in central Manitoba [105], and managers at the Mississippi Sandhill Crane National Wildlife Refuge have documented family groups returning to breeding territories immediately after prescribed fire [48].

Fire may have variable effects on predation of sandhill crane eggs and chicks. One author suggests that severe wildfires in the Okefenokee Swamp, Georgia, improved Florida sandhill crane nesting habitat by eliminating the woody vegetation that supported mammalian predators of eggs and chicks [12]. In contrast, another author hypothesized that fires set by local farmers in southern Michigan destroyed nesting cover and made nests and chicks vulnerable to both terrestrial and aerial predators [155]. It is likely that the impact of fire on nesting success varies among plant communities and predator populations.

Fire may have indirect negative impacts on nesting success in some areas. At Gray's Lake National Wildlife Refuge, researchers investigated greater sandhill crane nest success following 4 different treatments, each spanning dry upland to semipermanently flooded plant communities: continuously ungrazed, fall grazing of moderate intensity, summer grazing followed by 2 idle years, and fall prescribed fire followed by 2 ungrazed years [4]. Prescribed fires were conducted over 2 days in late October 1998 using a ring fire, with the objective of burning 100% of residual grass and rush vegetation on dry meadows and seasonally flooded areas, and 40% to 60% of tall emergent vegetation in semipermanently flooded areas. The fire removed most residual vegetation and litter; 3 burned sites were devoid of most residual graminoid and litter cover until new vegetation growth began the following spring. Wetter areas retained larger unburned areas after treatment [5]. All treatments were replicated 3 times. Compared to pretreatment years, greater sandhill crane nest success was significantly lower in the 2 years following prescribed fire (21.7% vs. 51.4%; P=0.038), which was attributed to the fire's consumption of most residual vegetation, limiting nesting materials and potential nesting cover [4]. However, nest success tended to increase the 2nd postfire year [9]. Grazing treatments appeared to have much less impact on residual vegetation than fire, with no treatment effect on nesting success detected in grazed or ungrazed sites [4].

At Malheur National Wildlife Refuge in southeastern Oregon, greater sandhill crane nest success was reduced by 55% the year after a prescribed fire, though burning did not influence nest fate after 1 season's growth. Compared to ungrazed fields, nests in burned fields were 70% less likely to be successful 1 year after fire. The author suggests that poor nest success was related to the amount of concealing vegetation consumed during the fire. Additionally, fire may have reduced the abundance of alternative prey (e.g., voles) available to predators, increasing pressure on nesting sandhill cranes. However, the author suggests that the short-term negative consequence of burning on nest success was outweighed by the long-term benefits to foraging habitat [64,65].

FIRE REGIMES:
Sandhill cranes occur in plant communities with a wide range of fire regimes, making generalizations difficult and requiring that managers identify the likely fire regime characteristics for their particular area. Sandhill cranes occur in areas that may typically experience low-severity fire (e.g., California oak woodlands, mesquite savanna, Gulf Coast wet pine savanna), mixed-severity fire (e.g., Wyoming riparian, Douglas-fir (cold)), or stand-replacement fire (e.g., mountain big sagebrush, California grassland, southern shortgrass or mixed-grass prairie, persistent lodgepole pine). Return intervals may be either short (e.g., southern shortgrass or mixed-grass prairie, Everglades sawgrass, southeast floodplain marsh) or long (e.g., Great Plains floodplain, northern hardwood maple-beech-eastern hemlock). Because fire regimes typical of many wetland plant communities are likely related to fire regimes in adjacent upland communities, refer to the complete FEIS Fire Regime Table for upland plant community fire regime information. FEIS also provides reviews of many of the plant species important to the life history and habitat use of sandhill cranes. See FEIS reviews for additional information, including information on fire regimes and fire effects, on species of interest.

Sandhill cranes also occur in geographic areas not covered by the Fire Regime Table, including a variety of tundra and boreal forest plant communities in Canada and Alaska, as well as plant communities in Mexico and Cuba. Available information on fire regimes in these areas is summarized below. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find Fire Regimes".

Northern fire regimes: Fire regimes in arctic, subarctic, and boreal peatlands are characterized by infrequent surface fires on open sites and infrequent combination crown and ground fires on forest and shrubland sites. Climate, substrate moisture regimes, and fuel loads affect the size, frequency, and depth of peatland fires [55]. Fire-return intervals in northern peatlands are estimated at 120 years on bog borders and 140 years on deep peat [123]. Based on observations, aerial photos, and fire maps, one study estimated that return intervals for peat fires range from 75 to 1,000 years, depending on the region and peatland type [163]. In macrofossil and charcoal analyses of peatland sites across boreal Alberta, Saskatchewan, and Manitoba, another study found that for the past 2,500 years, fire return intervals averaged 1,150 years [71].

In the interior taiga of Alaska, black spruce-paper birch/bog blueberry-bog Labrador tea and black spruce/bog blueberry-bog Labrador tea/Schreber's big red stem moss vegetation types characteristically have fire return intervals of less than 100 years [40]. From fire scar data, a mean fire-return interval of 40.4 years was calculated for the jack pine-black spruce/bog Labrador tea/reindeer lichen (Cladina spp.) vegetation type that occupies north-facing slopes and depressions of the Athabasca Plains of northeastern Alberta and northwestern Saskatchewan [24]. A fire interval of 69 years was estimated for boreal white spruce forests in Wood Buffalo National Park, Alberta. From fossil pollen and charcoal sediment records taken from Rainbow Lake, researchers estimate that 12 large fires burned in the 840 year time period (1160-2000). Data were collected from a single site in this study, and reconstruction potential was limited [74].

Cuban fire regimes: There is some evidence that tropical pine forests are adapted to and historically experienced frequent fire [29,92], though as of 2009 fire regime information was not found for plant communities in Cuba.

Fire exclusion: Fire historically maintained the open habitat preferred in many areas occupied by sandhill cranes [11,12,27,42,58,59,107], and in some cases, such as in the Okefenokee Swamp, even created the lakes and wetlands critical to certain populations of sandhill cranes [12,27]. Fire ignited by humans may also have created habitat for sandhill cranes, including annual fires set by Native Americans ([58], review by [124]) or fires set by early European settlers for land-clearing [104] or to improve cattle forage [96,151]. Fire regimes in many areas where sandhill cranes occur are much different now than historically [107]. Human settlement and increased water levels due to dike construction [11,12] may prevent the occurrence of fire. Fire exclusion is commonly mentioned as a factor contributing to habitat loss and consequently to the decline or limitation of sandhill crane populations in some areas [42,58,107,154,161].

FIRE MANAGEMENT CONSIDERATIONS:
Prescribed fire is often used to improve sandhill crane habitat degraded by fire exclusion, fire suppression, or other land management practices [42,57,107,120,127,131,132,143,160,161]. Prescribed fire reduces encroaching vegetation [42,57,100,107,143], thereby improving foraging [120,143], roosting [131], and nesting ([48,143], review by [150]) habitat. Prescribed fire may also be useful in attracting sandhill cranes to one area to relieve problematic sandhill crane congregations in another area. At Paynes Prairie, Florida, one justification for using prescribed fire to create suitable winter foraging habitat is that it reduces large concentrations of sandhill cranes in undesirable areas, such as private lands, and decreases the chances of heavy crop damage, disease transmission, pesticide contamination, or large-scale mortality from a catastrophic event [160].

Despite its widespread use, there is little published information available regarding the planning and implementation of prescribed fire treatments in the context of sandhill crane management. Because sandhill cranes inhabit such a wide variety of habitats, have different habitat needs throughout the year, prefer habitat consisting of some elements that are not generally affected by fire (e.g., standing water), and have variable timing of life history events depending on subspecies, it is highly recommended that managers consider the full sandhill crane life history and factors determining preferred habitat when incorporating fire into sandhill crane management. See Biological data and habitat requirements for life history and preferred habitat information. This section summarizes a few of the issues related to the habitat requirements and life history of sandhill cranes that should be considered when planning prescribed fires.

Prescribed fire at the Mississippi Sandhill Crane National Wildlife Refuge. Photo courtesy of US Geological Survey.

Pre-nesting: There is some concern that conducting prescribed fires prior to nesting could remove potential nesting material from the landscape [1,4,45,48,64,65]. Managers conducting prescribed fires at the Mississippi Sandhill Crane National Wildlife Refuge left 1 to 2 acres (0.4-0.8 ha) of core nesting habitat unburned to prevent the loss of nesting material. Over several years, managers noted that the unburned areas degraded into a pine-shrub scrub unsuitable for nesting, with pairs nesting instead in wet pockets, ponds, or burned areas, where they used twigs for nest material instead of grasses. This management strategy was consequently terminated, though a few pairs delayed nesting a year, possibly because of reduced nesting material availability [48].

Nesting: The available literature suggests that prescribed fire should be conducted outside of the nesting season and after young are mobile ([48,132,151], review by [150]). See Nesting dates and Egg hatching for more information on the timing of nesting activities for different sandhill crane populations. The ability of sandhill cranes to renest after an initial failure [4,9,14,31,35,48] may mean that successful breeding could occur if a first nest was destroyed by fire.

During the breeding season, sandhill cranes may be sensitive to the disturbance associated with prescribed fire, including the use of heavy equipment, low-flying aircraft, engines, and firefighters on the ground. This type of disturbance may lead to nest abandonment even when the nest is outside of the prescription area. At the Mississippi Sandhill Crane National Wildlife Refuge, disturbance from heavy equipment working on a fireline near a nest was blamed for nest abandonment. A second nest was abandoned due to the noise of heavy equipment traveling on a road within 820 feet (250 m) of the nest [48].

Activities associated with suppressing fire may also influence sandhill crane nesting. Trenched firelines may reduce surface and groundwater levels in wetlands, leading to changes that may influence sandhill crane habitat use. In Florida, small wet prairies were used as nesting sites by Florida sandhill cranes; similar wet prairies rimmed by shallow firelines (< 0.2 inches (0.5 cm)) were not used by nesting sandhill cranes and contained plant species indicative of an altered hydroperiod [7].

Captive sandhill cranes: Though not a concern for most managers, consideration of captive sandhill cranes is necessary at the Mississippi Sandhill Crane National Wildlife Refuge. Conducting prescribed fires near captive-reared Mississippi sandhill cranes in holding pens during acclimation and early post-release periods may cause increased stress, injuries within the pen, and premature dispersal into hazardous areas (i.e., places with more predators, chances of powerline collisions) [48].

Roosting: Fire activity just before dusk or just after dawn near known roosting areas may result in sandhill cranes flushing from safe roosting areas into more hazardous areas [48].

Season of treatments: Managers may need to balance considerations of sandhill crane life history events with a knowledge of fire effects on local vegetation. Because the majority of prescribed burning is done to improve habitat, usually by removing encroaching vegetation, managers may need to consider the season in which target vegetation would be most affected by fire. For example, at the Mississippi Sandhill Crane National Wildlife Refuge, dormant-season fire maintained open habitat but did not necessarily improve it by reducing woody vegetation. Growing-season prescribed fire was more successful at reducing woody vegetation [48].

Repetition of treatments: To maintain preferred habitat conditions, repeated use of prescribed fire may be necessary. The optimum frequency of treatments is related to local fire regimes and consequently varies across the range of sandhill cranes (See Fire regimes). At the Mississippi Sandhill Crane National Wildlife Refuge, prescribed fire needs to be applied every 2 to 3 years to best mimic historical disturbance, preferably in the growing season of March to June. If a growing-season fire is not possible, units are burned at some point between October and February [48]. At Paynes Prairie in northern Florida, the Florida Department of Natural Resources implemented a prescribed fire program with a 3-year rotation [160]. In Idaho, it is recommended that fall prescribed burning be conducted no more than every 2 years to allow vegetation to regenerate [9].

Size of treatments: Sandhill cranes may experience large wildfires, like those of the Okefenokee Swamp in the 1950s where >400,000 acres (160,000 ha) burned [27]. However, most fire prescriptions are much smaller, with documented treatments ranging from 16 to 2,095 acres (7-848 ha) [18,57,95]. One author cautions against the use of "large burns" when managing for sandhill cranes. Results from this study suggested that "cranes are flexible and can shift territories or nest sites in response to annual conditions. However, large burns may be more detrimental than small burns because they force more shifts in territory boundaries (e.g., increased strife with neighboring cranes, or reduced territory quality). Also, large burns may have correspondingly large effects on the distribution of predators and alternative prey. Perhaps most importantly, the recruitment failure in the burned area, despite high nest success, demonstrates that consideration of management practices must consider potential effects on the entire recruitment process, not simply nest success" [9].

Integration with other treatments: Prescribed fire is often integrated with other treatments, including haying, grazing, water manipulation, and mechanical treatments, to manage for sandhill cranes [5,9,57,107,127,131,150]. In some cases, particularly where prescribed fire may not achieve the removal of encroaching vegetation as desired, or where fire use is limited due to proximity to the wildland-urban interface, mechanical treatments may be used. At the Lillian Annette Rowe Sanctuary along the Platte River, Nebraska, early attempts to use fire to clear vegetation from river channel islands used for roosting showed minimal success due to a lack of fuel. Subsequent attempts at habitat improvement combined mechanical treatments with prescribed fire [131]. At the Mississippi Sandhill Crane National Wildlife Refuge, mechanical treatments are used instead of prescribed fire in areas within the wildland-urban interface to improve nesting habitat for several Mississippi sandhill crane pairs. The success of these treatments is not reported [48].

• Managers respect a 1,600-foot (500 m) disturbance buffer around nests, only working within that buffer under "carefully chosen circumstances".
• If nests fail, units may be burned within the first few weeks after failure only, to allow for potential renesting.
• Burn units with a family that includes a prefledged chick are generally not burned until after the chick is able to fly.
• Burn units with families nearby will only be burned if the family is at least 980 ft (300 m) from the burn unit boundary. In a few instances, particularly when one family member has a radiotransmitter, mobile family groups may be herded out of burn units while fires are conducted.
• During the dormant season, units are not burned while juvenile sandhill cranes are in holding pens or are in the acclimation or post-release period.
• Mechanical treatments are sometimes used as a surrogate for prescribed fire in nesting territories that are in the wildland-urban interface [48].

APPENDIX: FIRE REGIME TABLE

REFERENCES

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3. Anderson, James T.; Tacha, Thomas C.; Muehl, George T. 2000. Use of wetland and deepwater habitat by wintering sandhill cranes in coastal Texas. The Southwestern Naturalist. 45(1): 76-79. [74466]

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