Index of Species Information
WILDLIFE SPECIES: Molothrus ater
Introductory
WILDLIFE SPECIES: Molothrus ater
AUTHORSHIP AND CITATION :
Sullivan, Janet. 1995. Molothrus ater. 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/moat/all.html [].
ABBREVIATION :
MOAT
COMMON NAMES :
brown-headed cowbird
cowbird
buffalo bird
TAXONOMY :
The currently accepted scientific name for brown-headed cowbird is
Molothrus ater (Boddaert) [4,57]. It is a member of the family
Emberizidae [35]. The three recognized subspecies are as follows:
M. a. ssp. ater, brown-headed cowbird
M. a. ssp. obscurus, dwarf cowbird
M. a. ssp. artemisiae, western or sagebrush cowbird [3,4,35].
Introgression between western and dwarf cowbirds has been occurring
since contact in the 1930's in the Sierra Nevada. The size of western
cowbirds in the area of overlap has been decreasing [21].
ORDER :
Passeriformes
CLASS :
Bird
FEDERAL LEGAL STATUS :
No special status
OTHER STATUS :
NO-ENTRY
WILDLIFE DISTRIBUTION AND OCCURRENCE
WILDLIFE SPECIES: Molothrus ater
GENERAL DISTRIBUTION :
Breeding Range: The range of brown-headed cowbird extends from
southeastern Alaska, northern British Columbia, southern Mackenzie
District, northern Alberta, and north-central Saskatchewan; east to
southern Manitoba and southern Newfoundland; south to central Florida,
the Gulf Coast, and southern Texas; and south in Mexico to Oaxaca and
northern Baja California [57].
Winter Range: The brown-headed cowbird winters from northern
California, central Arizona, the Great Lakes States, and New England
south to Mexico, the Gulf Coast, and southern Florida [11].
Ranges of subspecies are as follows:
Brown-headed cowbird - Midwest and eastern United States
Western cowbird - western states including California
Dwarf cowbird - Great Basin and California [35].
ECOSYSTEMS :
FRES10 White-red-jack pine
FRES11 Spruce-fir
FRES12 Longleaf-slash pine
FRES13 Loblolly-shortleaf pine
FRES14 Oak-pine
FRES15 Oak-hickory
FRES16 Oak-gum-cypress
FRES17 Elm-ash-cottonwood
FRES18 Maple-beech-birch
FRES19 Aspen-birch
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES22 Western white pine
FRES23 Fir-spruce
FRES24 Hemlock-Sitka spruce
FRES25 Larch
FRES26 Lodgepole pine
FRES27 Redwood
FRES28 Western hardwoods
FRES29 Sagebrush
FRES30 Desert shrub
FRES31 Shinnery
FRES32 Texas savanna
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES35 Pinyon-juniper
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES38 Plains grasslands
FRES39 Prairie
FRES40 Desert grasslands
FRES41 Wet grasslands
FRES42 Annual grasslands
FRES44 Alpine
STATES :
| AL |
AK |
AZ |
AR |
CA |
CO |
CT |
DE |
FL |
GA |
| ID |
IL |
IN |
IA |
KS |
KY |
LA |
ME |
MD |
MA |
| MI |
MN |
MS |
MO |
MT |
NE |
NV |
NH |
NJ |
NM |
| NY |
NC |
ND |
OH |
OK |
OR |
PA |
RI |
SC |
SD |
TN |
TX |
UT |
VT |
VA |
WA |
WV |
WI |
WY |
DC |
| AB |
BC |
MB |
NB |
NF |
NT |
NS |
ON |
PE |
PQ |
| SK |
YK |
|
|
|
|
|
|
|
|
BLM PHYSIOGRAPHIC REGIONS :
1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands
KUCHLER PLANT ASSOCIATIONS :
The brown-headed cowbird occurs in all or nearly all Kuchler types.
SAF COVER TYPES :
The brown-headed cowbird occurs in all or nearly all SAF types.
SRM (RANGELAND) COVER TYPES :
The brown-headed cowbird occurs in all or nearly all SRM types.
PLANT COMMUNITIES :
In Maryland and the District of Columbia, brown-headed cowbirds inhabit
agricultural areas and adjacent woodlands [64].
In the central and southeastern oak (Quercus spp.)-pine (Pinus spp.)
region, brown-headed cowbirds are common to abundant in all successional
stages of central hardwood forest. They are present to common in
loblolly pine (P. taeda)-shortleaf pine (P. echinata) stands in early
stages of succession, but not present in mature loblolly-shortleaf pine
stands [13].
In Kansas a census of floodplain tallgrass prairie taken from 1974 to
1988 revealed 15.4 brown-headed cowbirds per square mile (6/sq km) in
the prairie, but less than 2.6 per square mile (1/sq km) in adjacent
wetlands.
In southwestern South Dakota brown-headed cowbirds are present in Rocky
Mountain juniper (Juniperus scopulorum) communities where fields or
grasslands were interspersed with shrubs or trees. Brown-headed
cowbirds use closed deciduous woodlands (riparian areas) for
reproductive activities [58].
In Texas on the Rio Grande plain, brown-headed cowbirds are common in
thorn forests dominated by blackbrush (Acacia rigidula), guajillo (A.
berlandieri), Texas persimmon (Diospyros texana), and other thorny
shrubs. They are also present in adjacent grasslands and areas cleared
of shrubs for agriculture and cattle grazing [69].
On the lower Colorado River in Arizona, the brown-headed cowbird was one
of a number of granivores that reached their highest densities in common
reed (Phragmites spp.) communities in fall, winter, and spring [1].
Brown-headed cowbirds are more numerous in riparian stands of Fremont
cottonwood (Populus fremontii) than in nearby mesquite (Prosopis spp.)
bosques or saltcedar (Tamarix ramosissima) stands [61].
In southern California brown-headed cowbirds sucessfully breed in
chaparral communities [71].
In Washington shrub-steppe communities dominated by big sagebrush
(Artemisia tridentata) and rubber rabbitbrush (Chrysothamnus nauseosus),
brown-headed cowbirds occurred on 38.7 percent of transects. There was a
positive correlation between observations of brown-headed cowbirds and
big sagebrush cover. The presence of brown-headed cowbirds in this
ecosystem is apparently recent. Shortly after settlement unbroken
sagebrush and bunchgrass landscapes were rapidly degraded and fragmented
by conversion to agriculture and cattle range, creating feeding habitat
for brown-headed cowbirds [14].
REFERENCES :
NO-ENTRY
BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Molothrus ater
TIMING OF MAJOR LIFE HISTORY EVENTS :
Diurnal Activity: In the Sierra Nevada during the breeding season,
brown-headed cowbirds spend the early morning hours in host-rich
forests, then commute up to 2.7 miles (6.7 km) to prime feeding sites
such as residential developments (especially where bird feeders are
present) and horse corrals. Flocks of up to 30 brown-headed cowbirds
may develop at feeding areas. Evening roosting behavior depends on
locality. In the Sierra Nevada flocks of brown-headed cowbirds roost
in willow (Salix spp.) thickets, away from both feeding and breeding
areas. The flocks disperse to breeding areas in the early morning
[51,70].
Spring Migration: The brown-headed cowbird is a short-distance migrant
within North America. In the Northeast most brown-headed cowbirds
travel 300 to 340 miles (800-850 km) between breeding season banding and
winter recovery. Brown-headed cowbirds travel during the day, often as
part of large mixed-species flocks with other blackbirds: red-winged
blackbirds (Agelaius phoeniceus), common grackle (Quiscalus quiscula),
European starling (Sturnus vulgaris), and, less frequently, Euphagus
blackbirds and American robins (Turdus migratorius) [35]. In Maryland
and the District of Columbia, spring movements of brown-headed cowbirds
occur from February 5 to April 25, with a peak of activity from March 10
to April 10 [64].
Mating Systems and Pair Bonding: Brown-headed cowbird mating systems
have been variously reported as monogamous, polygynous, and polygamous
[35,51]. Rothstein and others [51] reviewed reports on mating systems
and could come to no conclusion. Different mating systems may occur
with different densities or sex ratios; males guard mates more
frequently in low density populations. Pair bonding is difficult to
assess due to the difficulty of defining a pair. Bonding may be brief
or season-long [35].
Nesting: The brown-headed cowbird is a brood parasite; no nest is built
and the eggs are laid in the nests of other birds (host species). In
Maryland and the District of Columbia, brown-headed cowbirds lay eggs
from late April to late July, with the peak from early May to early
July. Extreme dates are April 24 and July 28 [64]. In Missouri
brown-headed cowbirds eggs have been present in nests from mid-April
until mid-July [35].
Nests: Female brown-headed cowbirds choose the nest, finding nests in
one of three ways. They may perch in a hidden spot, watching for nest
building activity in nearby open areas; walk on the ground watching for
activity; or search noisily on short flights appearing to intentionally
flush potential hosts from nests [35]. Preferred host nests have eggs
present. Host eggs are usually of smaller volume than brown-headed
cowbird eggs. Preferred nests are active; eggs are added on a daily
basis by the host female. Large diameter (greater than 3 inches [7.6
cm]) closed nests are preferred over small diameter (less than 2 inches
[5.1 cm]) open and closed nests. Large, open nests are least preferred.
Clutch: Brown-headed cowbirds lay eggs in "sequences" of one to seven
eggs (laid daily with pauses of 1 or more days between eggs) and rest
periods of at least 2 days between sequences throughout the breeding
season [54].
Incubation: Since incubation depends on host nesting activity it is
difficult to assess; incubation may be as short as 10 days but is
probably 11 to 12 days. Brown-headed cowbird eggs laid the same day as
host eggs usually hatch first [35].
Development of Young: Brown-headed cowbird hatchlings are altricial and
remain in the nest. Growth is rapid. Brown-headed cowbird nestlings
emerge from the nest onto nearby branches at 8 to 13 days. Short
flights are attempted at 11 days. Fledglings continue to be fed by host
parents until 16 to 28 days after leaving the nest [35].
Territoriality: In the eastern Sierra Nevada, where both hosts and
brown-headed cowbirds are widely dispersed on the breeding areas, there
is no apparent territoriality. Elsewhere, such as in the eastern states
where brown-headed cowbirds are moderately abundant and competition for
host nests is higher, territorial defense is typical. At very high
brown-headed cowbird densities, territoriality is apparently not cost
effective and is rarely observed [51].
Resistant Hosts: Vireos (Vireo spp.) and some warblers (i.e., yellow
warbler [Dendroica petechia]) cover brown-headed cowbird eggs with a new
floor and lay their own eggs on top of it. Yellow-breasted chats
(Icteria virens) abandon nests with foreign eggs [36]. American robins
and gray catbirds (Dumetella carolinensis) usually eject foreign eggs
from the nest. Instances of brown-headed cowbird nest parasitism in
gray catbird nests apparently occur when the brown-headed cowbird egg is
laid before a gray catbird has laid any of its own eggs and has learned
to recognize its own eggs [34,36].
Fall Migration: On western slopes of the Sierra Nevada, juvenile
brown-headed cowbirds began to form flocks as independence was achieved.
The first independent juveniles appeared on July 14. In the same area
all adult brown-headed cowbirds left between July 17 and July 21. In
Maryland and the District of Columbia, fall movements occur from August
15 to December 10, with peak activity from September 25 to November 1
[64].
Roosting Behavior: In the nonbreeding season, brown-headed cowbirds
spend the night in large mixed-species roosts with other blackbirds
[40]. Mixed-species roosts in Kentucky may be as large as 5 million
birds, 2 to 5 percent of which are usually brown-headed cowbirds.
Oklahoma roost numbers peak in November with 250 to 900 thousand birds
[35].
Demography: Males are sexually mature at 1 year but rarely copulate
until they are 2 years old. Females breed at 1 year [35]. Female
brown-headed cowbirds may lay up to 40 eggs in a season [52]. Stable
populations of brown-headed cowbirds would be maintained by 2.5 percent
survival rate and lifetime fecundity of 80 eggs per female. Annual
adult survivorship is 48.5 percent for males and 40.4 percent for
females. The longevity record is 15 years, 10 months for a banded male [35].
Mortality Factors: Lowther [35] reviewed reports of ectoparasites,
helminth parasites, and infectious bacteria in brown-headed cowbirds.
PREFERRED HABITAT :
Brown-headed cowbirds prefer open habitats of low or scattered trees
interspersed with grasslands; they usually avoid unbroken forest. They
prefer, and may require, areas of short grass or bare ground for
foraging [50]. Open coniferous and deciduous woodlands, forest edges,
brushy thickets, agricultural land, and suburban areas are all
acceptable brown-headed cowbird habitat [11,24]. In the Sierra Nevada
brown-headed cowbirds are largely or completely absent from extensive
stands of old-growth forest. They are rare in meadow and riparian areas
more than 16 miles (10 km) from centers of human activities. In areas
close to human activities, brown-headed cowbirds were observed in
meadow-edge communities more often than in clearcuts, partially logged
forests, or uncut forests [70]. In Saskatchewan aspen (Populus spp.)
parklands, brown-headed cowbird abundance increased with increasing
grove size; however, brown-headed cowbirds occupied even very small
groves [29]. In the western states the brown-headed cowbird is more
abundant in second-growth than in old-growth forests, and more abundant
in stands surrounded by a large amount of open land [25]. In North
Dakota mixed-grass prairie, brown-headed cowbird density was higher on
plots with shrubs present than on shrubless plots [5]. In Texas
loblolly pine plantations less than 10 years old, brown-headed cowbirds
were more abundant on plots with snags than on snagless plots [12].
In Pennsylvania a mosaic of even-aged aspen stands (various ages) and
mixed-oak stands (either mature or early successional) was assessed for
use of edges by birds. In mature aspen stands, there was no difference
between brown-headed cowbird use of edge and interior. In stands that
were cut less than 10 years prior to the survey, brown-headed cowbirds
only occupied edges, and they were not present in recently cut (less
than 2 years) stands. In mature oak stands, brown-headed cowbird use
was confined largely to edges; in stands cut less than 10 years prior to
the survey a few brown-headed cowbirds were observed in the interior and
none on the edges [72].
COVER REQUIREMENTS :
Female brown-headed cowbirds use perches to spot potential host nests;
areas with hidden perches are preferred (i.e., shrubs in grass-dominated
communities) [35].
In Ohio autumn roosts were usually in dense stands of deciduous trees on
moist soils; tree crowns were generally narrow, vertical, and dense [40].
In the Southeast brown-headed cowbirds commonly roost in thickets [24].
FOOD HABITS :
The brown-headed cowbird is a ground gleaner, consuming weed seeds,
grass seeds, waste grain, and insects. Historically it may have
depended on grazing by large ungulates to create suitable feeding
conditions. A common foraging technique is to follow large grazing
animals, gleaning seeds and the insects stirred up by the feet of the
grazer [11,39,35]. Brown-headed cowbirds also feed on insects present
on large ungulates; they have been observed walking on resting bison
(Bison bison), picking insects from the hide [39]. In the northeastern
United States plant foods common in brown-headed cowbird diets include
seeds of bristle grasses (Setaria spp.), ragweeds (Ambrosia spp.), oats
(Avena spp.), corn (Zea mays), crab grasses (Digitaria spp.), knotweeds
and smartweeds (Polygonum spp.), paspalums (Paspalum spp.), and
sheepsorrel (Rumex spp.). In the Southeast plant foods include seeds of
bristle grasses, panic grasses (Panicum spp.), ragweeds, oats, wheat
(Triticum spp.), doveweeds (Croton spp.), corn, and paspalums [36]. A
summary of several dietary studies reveals that approximately 75 percent
of the brown-headed cowbird diet is weed seeds; grasshoppers and beetles
form the larger part of the remaining 25 percent of the diet [35].
PREDATORS :
In northeastern Arkansas short-eared owl (Asio flammeus) pellets
contained brown-headed cowbird remains [60]. Predators on fledglings
include black racer (Coluber constictor), black rat snake (Elaphe
obsoleta), and blue jay (Cyanocitta cristata). Brown-headed cowbirds
join in mobbing great horned owls (Bubo virginianus), a potential
predator of both adults and young [35].
MANAGEMENT CONSIDERATIONS :
Range Expansion: Historically brown-headed cowbirds were largely
confined to the mid-continental prairies where they presumably followed
herds of nomadic bison, and perhaps pronghorn (Antilocapra americana)
and elk (Cervus canadensis) as well [46]. The brown-headed cowbird
underwent a rapid range expansion with habitat alterations due to forest
clearing, domestic cattle grazing, urbanization, and conversion of
forested habitats to agricultural land [46]. It invaded the Great Lakes
States and the Northeast during the nineteenth century [44].
Root and Weckstein [49] reported that brown-headed cowbird winter range
has recently expanded into Maine and Nova but has contracted elsewhere,
particularly Pennsylvania, Michigan, Wisconsin, Iowa, Montana, and
Washington. He speculated that the trapping of brown-headed cowbirds in
Michigan (for preservation of the Kirtland's warbler [Dendroica
kirtlandii]) that removed more than 40,000 brown-headed cowbirds was
partly responsible for this unexpected phenomenon. Breeding Bird Survey
(BBS) data from 1965 to 1979 indicate that brown-headed cowbirds have
been increasing in the Southeast, including the Carolinas and southern
Georgia [44]. Colonization of the Sierra Nevada by brown-headed
cowbirds has taken place in the last 50 years [51]. Expansion into the
western states is due largely to rapid colonization by dwarf cowbirds
[32,50]. Rothstein [50] stated that the separation of breeding and
feeding areas has allowed much of this range expansion. Since
brown-headed cowbirds can commute up to 3 miles (7 km) between breeding
areas and feeding areas, creation of feeding habitat (i.e., pack
stations, horse corrals, suburban developments, and bird feeders) within
formerly continuous forest has opened new areas for brown-headed cowbird
breeding [50]. In the Sierra Nevada brown-headed cowbird numbers
dropped sharply with distance from pack stations; they were always
present when horses were present [70].
Population Status: Estimates of the North American population of
brown-headed cowbirds range from 20 to 40 million individuals [63].
Graber and Graber [76] estimated the 1957 brown-headed cowbird
population of Illinois as 1.1 million. The estimated brown-headed
cowbird population in North Dakota in 1972 was approximately 1 million,
with a maximum density of 15.2 pairs per square mile (5.9 pairs/sq km)
[63].
Brown-headed cowbird populations have increased throughout the twentieth
century in most sections of the United States. In the Northeast,
brown-headed cowbirds have experienced a statistically significant
population decrease [59]. A ranking system for neotropical migrants
(including brown-headed cowbird) listed the population trend for
brown-headed cowbird in Alaska as unknown (no data), decreasing in
Arizona (uncertain due to small size of the BBS), slightly increasing in
Idaho (also uncertain due to small BBS sample), and sharply increasing
in Montana [75]. In Oregon brown-headed cowbird populations increased
in juniper woodlands between 1899 and 1983, although they decreased
significantly statewide [35,55]. In the Sierra Nevada brown-headed
cowbird populations increased between 1966 and 1985 [43]. Breeding Bird
Survey data for the Midwest suggest a decrease in brown-headed cowbird
populations for the period 1966 to 1981, but an increase from 1982 to
1991 [66]. Significant population increases (BBS data 1966-1987)
occurred in Georgia, North Carolina, Iowa, North Dakota, Utah, and
Colorado. Significant decreases occurred in Minnesota, Michigan,
Wisconsin, New York, Rhode Island, Ohio, Ontario, West Virginia,
Tennessee, New Brunswick, Oklahoma, and Texas [35]. Another
interpretation of BBS data indicates a generally negative trend for the
United States but a sharply increasing trend for Illinois during the
period 1966 to 1991 [26].
Host Species: Because of range expansion the brown-headed cowbird has
come into recent contact with many new potential host species, most of
which lack defenses against nest parasitism. Numbers of parasitized
species have increased in the last half century; new parasitism records
for species continue to be reported making estimation of the number of
parasitized species difficult. Stewart and Robbins [64] listed 223
parasitized species in the United States. In their area (Maryland and
the District of Columbia), the species most heavily parasitized were
red-eyed vireo (Vireo olivaceous), song sparrow (Melospiza melodia), and
chipping sparrow (Spizella passerina) [64]. In 1985, Friedmann and Kiff
[73] listed 240 species known to be parasitized, the majority of which
are neotropical migrant songbirds. Lowther [35] reported that 144
species have actually reared brown-headed cowbird young. Over the
entire United States the top 17 species with over 100 records of fledged
brown-headed cowbirds are yellow warbler, song sparrow, red-eyed vireo,
chipping sparrow, eastern phoebe (Sayornis phoebe), rufous-sided towhee
(Pipilo erythrophthalmus), ovenbird (Seiurus aurocappilus), common
yellowthroat (Geothylpis trichas), American redstart (Setophaga
ruticilla), indigo bunting (Passerina cyanea), yellow-breasted chat,
red-winged blackbird, Kentucky warbler (Oporomis formosis), willow
flycatcher (Empidonax traillii), Bell's vireo (Vireo bellii),
yellow-throated vireo (V. flavescens), and field sparrow (Spizella
pusilla) [35]
Brown-headed cowbirds reduce host productivity because 1) females remove
one egg from 33 to 90 percent of host nests, 2) brown-headed cowbird
eggs are thick-shelled, often causing breakage of host eggs, 3)
brown-headed cowbird eggs have a shorter incubation period than those of
host species, 4) host nestlings are usually smaller and less aggressive
than brown-headed cowbird nestlings, and 5) brown-headed cowbird
nestlings grow more rapidly, beg louder, and have larger gapes (bigger
mouths) than host nestlings [46].
Threats to Endangered Species: Brown-headed cowbird parasitism is one
of the variables used in a scoring method to determined species
prioritization for songbird conservation [28]. Several neotropical
migrant songbirds with restricted ranges are endangered at least partly
as a result of brown-headed cowbird nest parasitism, including
Kirtland's warbler [37,48], Bell's vireo [42,48], golden-cheeked warbler
(Dendroica chrysoparia) [48], black-capped vireo (V. atricapillus), and
willow flycatcher [46,48,53]. The precise effect of nest parasitism on
willow flycatcher has not been clearly established, however. For willow
flycatcher and most of the other endangered species affected by
brown-headed cowbird parasitism, there is a complex interaction between
direct effects due to habitat loss and indirect effects related to nest
parasitism [50].
Threat to Other Species: Brown-headed cowbirds pose a potential threat
to many neotropical migrant songbirds. Brown-headed cowbirds feed
mostly in short grass communities including shortgrass prairie,
pastures, and lawns; and on bare ground. Feeding areas are enhanced by
human activities [46]. At least 10 species of songbirds have declined
since brown-headed cowbirds have expanded their range into California,
possibly due to brown-headed cowbird nest parasitism [50]. On the
western slopes of the Sierra Nevada, no host species is immediately
threatened, but increased human use of backcountry areas and increased
fragmentation of dense forests will increase potential feeding areas for
brown-headed cowbirds [70]. Low intensity monitoring for neotropical
migrant conservation may include checks for cowbird parasitism every 3
years in management areas; monitoring is recommended for the western
Sierra Nevada [15,70]. Airola [2] recommended that any development
activities should be far from the highest densities of potential host
species.
Parasitism Rates and Habitat Parameters: Brown-headed cowbird nest
parasitism has been enhanced by shifts in agricultural practice and
farmland structure in this century. There is a higher rate of
brown-headed cowbird parasitism near field edges with elevated perches
than away from field edges and perches [48]. Brown-headed cowbirds are
often more abundant on edges than in interior. Parasitism rates are
higher near forest edges and edges of prairie fragments [19]. In the
eastern deciduous forest, numbers of brown-headed cowbirds and rates of
parasitism decrease with distance from forest edges [9]. According to
Brittingham and Temple [9] forest fragmentation leads to higher levels
of nest parasitism by increasing the ratio of forest edge to forest
interior (defined as area more than 990 feet [300 m] from an edge). In
the Midwest brown-headed cowbird parasitism is negatively correlated
with forest cover [47]. Nest parasitism is low (less than 10% of all
potential host nests) in extensively forested sections of Mark Twain and
Hoosier National Forests (Missouri and Indiana, respectively) [46].
However, Robinson and others [47] reported that in a highly fragmented
landscape with a long history of brown-headed cowbird presence, there
was no appreciable decline in nest parasitism even more than 2,310 feet
(700 m) from the nearest edge. They speculated that in this area,
brown-headed cowbirds have saturated all available host nests because
brown-headed cowbird populations are high and host populations are
minimal. In addition, brown-headed cowbird populations in the most
highly fragmented areas may be more limited by host availability than
feeding sites or forest density [47].
In western states and particularly in the Sierra Nevada, availability of
local feeding areas such as livestock corrals and pack stations is
associated with increased levels of brown-headed cowbird nest parasitism
[46]. Bock and others [8] listed the brown-headed cowbird as either
unresponsive or showing mixed or uncertain response to grazing in
grasslands in the western states but showed a positive response to
domestic cattle grazing in shrub-steppe communities. Robinson and
others [46] concluded the magnitude of edge effect on brown-headed
cowbird parasitism rates varies within and among regions in relation to
landscape level variation in fragmentation and brown-headed cowbird
abundance.
Management Recommendations/Cowbird Control: Methods for removal of
brown-headed cowbirds from critical breeding habitat for neotropical
migrants include trapping and shooting individuals, and roost kills.
The use of baited decoy traps to capture and kill female brown-headed
cowbirds has reduced the rate of nest parasitism and increased nesting
success for a few species. It is thought that this action was the key
element in stabilizing populations of Kirtland's warbler [38,46]. In
1971 Mayfield [37] predicted that the Kirtland's warbler would be
extinct by 1980 if brown-headed cowbirds were not controlled. An
extensive program of trapping and shooting of brown-headed cowbirds was
initiated in 1972. The Kirtland's warbler population did not rebound,
but remained stabilized (with very low levels of nest parasitism) until
there was a slight population increase in 1991 and 1992 [38]. In other
cases use of decoys and shooting of female brown-headed cowbirds has
effectively reduced nest parasitism rates [32,46]. Removal of
brown-headed cowbirds from riparian habitats occupied by Bell's vireos
has resulted in increased Bell's vireo productivity [22].
It is not clear whether brown-headed cowbird trapping at the landscape
level would reduce nest parasitism in extensively fragmented landscapes
such as the Midwest. Large-scale elimination of brown-headed cowbirds
at winter roosts may reduce overall numbers of brown-headed cowbirds,
but this approach may not affect target songbird populations in breeding
habitats. Winter banding programs are needed to determine movements of
brown-headed cowbirds and the feasibility of winter trapping for
population reduction in critical areas [32].
The ethical implications of large-scale eradication of the brown-headed
cowbird, a native songbird, need to be considered [46]. The
brown-headed cowbird is protected under the Migratory Bird Treaty Act
[68]. Trapping and killing female brown-headed cowbirds is at best a
temporary solution to excessive nest parasitism. The most complete
solution is landscape level management including consolidation of
ownership to preserve large tracts of forest, reduction or elimination
of brown-headed cowbird feeding areas within large tracts, and
minimization of edge [47]. Shape of forest tracts influences the ratio
of edge to interior. Long narrow areas like riparian woodlands have
very little interior area. Forest tracts in simple square or circle
shapes have the greatest interior to edge ratios [19]. Riparian
corridors need to be wide [46]. In the case of willow flycatcher in
California, protection of high-elevation riparian areas and meadows from
grazing and/or pack animals is recommended to reduce the threat of
brown-headed cowbird parasitism [53]. Laymon [32] recommended
elimination of grazing near riparian areas and removal of feedlots,
stables, and dairies in critical areas, and reforestation of riparian
areas. Robbins and others [45] suggested that in the mid-Atlandtic
States, 7,410 acres (3,000 ha) of contiguous forest is the minimum
required for population maintenance of other songbirds in the presence
of brown-headed cowbird parasitism. Data from moderately fragmented
areas of the Midwest suggest that 49 thousand to 1.2 million acres
(20,000-50,000 ha) may be necessary. In Texas the Biological Advisory
Team [74] suggested that 4,940 to 12,700 acres (2,000-5,000 ha) are
needed to minimize the effects of brown-headed cowbird parasitism on the
golden-cheeked warbler [46].
REFERENCES :
NO-ENTRY
FIRE EFFECTS AND USE
WILDLIFE SPECIES: Molothrus ater
DIRECT FIRE EFFECTS ON ANIMALS :
There were no references in the literature concening direct or indirect
mortality of brown-headed cowbirds due to fire. Adults could easily
escape fire. Nests and young are vulnerable to fire but unlikely to be
exposed to fire because in most areas fire seasons are not coincident
with early nesting seasons. Literature references are mostly on the
topic of bird use of recently burned versus unburned plots.
Brown-headed cowbird use of burns is likely to be related to food
availability and availability of perches. It is also likely to be
related to the presence of host species nests.
In Connecticut a 1982 census revealed that brown-headed cowbirds were
more abundant on old fields that had been burned in spring of 1981 than
on unburned fields. Vegetation in these plots consisted of shrubs and
saplings (mostly red maple [Acer rubrum]) [17].
In Kansas a survey of birds was made on successional (i.e., undisturbed)
plots dominated by shrubs and prairie plots dominated by grasses that
had been mowed and burned. Brown-headed cowbirds occurred only on the
shrub plots; none were observed on the mowed and burned plots. There
was an extreme drop in the numbers of other bird species on the mowed
and burned plots as well [10]. On the Curtis Prairie, Wisconsin, there
was little difference between brown-headed cowbird recapture rates on
unburned plots and on recently burned plots [33].
In South Dakota a prescribed fire was conducted in mixed-grass prairie
in May 1983. A bird census was conducted on the burned area and on an
adjacent unburned area in June and July of the same year. Brown-headed
cowbirds were observed on both burned and unburned areas with no
significant differences in numbers of observations [27].
In Arizona an October 1973 census of nonbreeding birds in ponderosa pine
(Pinus ponderosa) stands showed brown-headed cowbirds with a slightly
higher prominence value (product of number of individuals and frequency
of occurrence) on unburned plots than on plots that had been burned by
wildfire in May 1972 [7].
HABITAT RELATED FIRE EFFECTS :
Effects of Fire Exclusion: Fire exclusion in mixed-grass prairie has
allowed shrubs to invade grasslands. In North Dakota brown-headed
cowbird density was higher on shrubby plots than on shrubless plots [5].
FIRE USE :
NO-ENTRY
FIRE REGIMES :
Find 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".
REFERENCES :
NO-ENTRY
REFERENCES
WILDLIFE SPECIES: Molothrus ater
REFERENCES :
1. Anderson, Bertin W.; Ohmart, Robert D.; Meents, Julie K.; Hunter,
William C. 1984. Avian use of marshes on the lower Colorado River. In:
Warner, Richard E.; Hendrix, Kathleen M., eds. California riparian
systems: Ecology, conservation, and productive management: Proceedings
of a conference; 1981 September 17-19; Davis, CA. Berkeley, CA:
University of California Press: 598-604. [5861]
2. Airola, Daniel A. 1986. Brown-headed cowbird parasitism and habitat
disturbance in the Sierra Nevada. Journal of Wildlife Management. 50(4):
571-575. [24948]
3. American Ornithologists' Union. 1957. Checklist of North American birds.
5th ed. Baltimore, MD: The Lord Baltimore Press, Inc. 691 p. [21235]
4. American Ornithologists' Union. 1983. Checklist of North American birds.
6th ed. Lawrence, KS: Allen Press, Inc. 877 p. [21234]
5. Arnold, Todd W.; Higgins, Kenneth F. 1986. Effects of shrub coverages on
birds of North Dakota mixed-grass prairies. Canadian Field-Naturalist.
100(1): 10-14. [23671]
6. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals,
reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's
associations for the eleven western states. Tech. Note 301. Denver, CO:
U.S. Department of the Interior, Bureau of Land Management. 169 p.
[434]
7. Blake, John G. 1982. Influence of fire and logging on nonbreeding bird
communities of ponderosa pine forests. Journal of Wildlife Management.
46(2): 404-415. [5114]
8. Bock, Carl E.; Saab, Victoria A.; Rich, Terrell D.; Dobkin, David S.
1993. Effects of livestock grazing on neotropical migratory landbirds in
western North America. In: Finch, Deborah M.; Stangel, Peter W., eds.
Status and management of neotropical migratory birds: Proceedings; 1992
September 21-25; Estes Park, CO. Gen. Tech. Rep. RM-229. Fort Collins,
CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain
Forest and Range Experiment Station: 296-309. [24618]
9. Brittingham, Margaret Clark; Temple, Stanley A. 1983. Have cowbirds
caused forest songbirds to decline?. Bioscience. 33: 31-35. [24949]
10. Cink, Calvin L.; Lowther, Peter E. 1989. Breeding bird populations of a
floodplain tallgrass prairie in Kansas. In: Bragg, Thomas B.;
Stubbendieck, James, eds. Prairie pioneers: ecology, history and
culture: Proceedings, 11th North American prairie conference; 1988
August 7-11; Lincoln, NE. Lincoln, NE: University of Nebraska: 259-262.
[14059]
11. DeGraaf, Richard M.; Scott, Virgil E.; Hamre, R. H.; [and others]. 1991.
Forest and rangeland birds of the United States: Natural history and
habitat use. Agric. Handb. 688. Washington, DC: U.S. Department of
Agriculture, Forest Service. 625 p. [15856]
12. Dickson, James G.; Conner, Richard N.; Williamson, J. Howard. 1983. Snag
retention increases bird use of a clear-cut. Journal of Wildlife
Management. 47(3): 799-804. [13855]
13. Dickson, James G.; Thompson, Frank R., III; Conner, Richard N.;
Franzreb, Kathleen E. 1993. Effects of silviculture on neotropical
migratory birds in central and southeastern oak pine forests. In: Finch,
Deborah M.; Stangel, Peter W., eds. Status and management of neotropical
migratory birds: Proceedings; 1993 September 21-25; Estes Park, CO. Gen.
Tech. Rep. RM-229. Fort Collins, CO: U.S. Department of Agriculture,
Forest Service, Rocky Mountain Forest and Range Experiment Station:
374-385. [24663]
14. Dobler, Frederick C. 1994. Washington State shrub-steppe ecosystem
studies with emphasis on the relationship between nongame birds and
shrub and grass cover densities. In: Monsen, Stephen B.; Kitchen,
Stanley G., compilers. Proceedings--ecology and management of annual
rangelands; 1992 May 18-22; Boise, ID. Gen. Tech. Rep. INT-GTR-313.
Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain
Research Station: 149-161. [24272]
15. Droege, Sam. 1993. Monitoring neotropical migrants on managed lands:
when, where, why. In: Finch, Deborah M.; Stangel, Peter W., eds. Status
and management of neotropical migratory birds: Proceedings; 1992
September 21-25; Estes Park, CO. Gen. Tech. Rep. RM-229. Fort Collins,
CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain
Forest and Range Experiment Station: 189-191. [10040]
16. Ehrlich, Paul R.; Dobkin, David S.; Wheye, Darryl. 1988. The birder's
handbook: a field guide to the natural history of North American birds.
New York: Simon & Schuster, Inc. 785 p. [21559]
17. Euler, David L.; Thompson, Daniel Q. 1978. Ruffed grouse and songbird
foraging response on small spring burns. New York Fish and Game Journal.
25(2): 156-164. [8077]
18. Eyre, F. H., ed. 1980. Forest cover types of the United States and
Canada. Washington, DC: Society of American Foresters. 148 p. [905]
19. Faaborg, John, Brittingham, Margaret; Donovan, Therese; Blake, John.
1993. Habitat fragmentation in the temperate zone: a perspective for
managers. In: Finch, Deborah M.; Stangel, Peter W., eds. Status and
management of neotropical migratory birds: Proceedings; 1993 September
21-25; Estes Park, CO. Gen. Tech. Rep. RM-229. Fort Collins, CO: U.S.
Department of Agriculture, Forest Service, Rocky Mountain Forest and
Range Experiment Station: 331-338. [24662]
20. Finch, Deborah M. 1991. Population ecology, habitat requirements, and
conservation of neotropical migratory birds. Gen. Tech. Rep. RM-205.
Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky
Mountain Forest and Range Experiment Station. 26 p. [22662]
21. Fleischer, Robert C.; Rothstein, Stephen I. 1988. Known secondary
contact and rapid gene flow among subspecies and dialects in the
brown-headed cowbird. Evolution. 42(6): 1146-1158. [24943]
22. Franzreb, Kathleen E. 1989. Ecology and conservation of the endangered
least Bell's vireo. U.S. Fish and Wildlife Service Biological Report
89(1). Washington, DC. 17 p. [24942]
23. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; [and others].
1977. Vegetation and environmental features of forest and range
ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of
Agriculture, Forest Service. 68 p. [998]
24. Hamel, Paul B.; LeGrand, Harry E., Jr.; Lennartz, Michael R.;
Gauthreaux, Sidney A., Jr. 1982. Bird-habitat relationships on
southeastern forest lands. Gen. Tech. Rep. SE-22. Asheville, NC: U.S.
Department of Agriculture, Forest Service, Southeastern Forest
Experiment Station. 417 p. [15423]
25. Hejl, Sallie J. 1992. The importance of landscape patterns to bird
diversity: a perspective from the Northern Rocky Mountains. Northwest
Environmental Journal. 8: 119-137. [22066]
26. Herkert, James R. 1994. The effects of habitat fragmentation on
midwestern grassland bird communities. Ecological Applications. 4(3):
461-471. [24146]
27. Huber, G. E.; Steuter, A. A. 1984. Vegetation profile and grassland bird
response to spring burning. Prairie Naturalist. 16(2): 55-61. [3264]
28. Hunter, William C.; Carter, Michael F.; Pashley, David N.; Barker,
Keith. 1993. The partners in flight species prioritzation scheme. In:
Finch, Deborah M.; Stangel, Peter W., eds. Status and management of
neotropical migratory birds: Proceedings; 1992 September 21-25; Estes
Park, CO. Gen. Tech. Rep. RM-229. Fort Collins, CO: U.S. Department of
Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment
Station: 109-119. [2433]
29. Johns, Brian W. 1993. The influence of grove size on bird species
richness in aspen parklands. Wilson Bulletin. 105(2): 256-264. [22269]
30. Kochert, Michael N. 1986. Raptors. In: Cooperrider, Allan Y.; Boyd,
Raymond J.; Stuart, Hanson R., eds. Inventory and monitoring of wildlife
habitat. Denver, CO: U.S. Department of the Interior, Bureau of Land
Management, Denver Service Center: 313-349. [13527]
31. Kuchler, A. W. 1964. Manual to accompany the map of potential vegetation
of the conterminous United States. Special Publication No. 36. New York:
American Geographical Society. 77 p. [1384]
32. Laymon, Stephen A. 1987. Brown-headed cowbirds in California: historical
perspectives and management opportunities in riparian habitats. Western
Birds. 18: 63-70. [24951]
33. Loiselle, Bette A.; Blake, John G. 1984. Site tenacity of birds on
Curtis Prairie, Dane County, Wisconsin. Passenger Pigeon. 46: 16-21.
[23228]
34. Lowther, Peter E. 1980. Gray catbirds rear brown-headed cowbirds.
Banding. 52(3): 29-30. [23361]
35. Lowther, Peter E. 1993. Brown-headed cowbird. In: Poole, A.; Gill, F.,
eds. The birds of North America. No. 47. Philadelphia, PA: THe Academy
of Natural Sciences; Washington, DC: The American Ornithologists' Union.
24 p. [24953]
36. Martin, Alexander C.; Zim, Herbert S.; Nelson, Arnold L. 1951. American
wildlife and plants. New York: McGraw-Hill Book Company, Inc. 500 p.
[4021]
37. Mayfield, Harold F. 1975. The numbers of Kirtlands's warblers. Jack-Pine
Warbler. 53(2): 39-47. [24989]
38. Mayfield, Harold F. 1993. Kirtland's warblers benefit from large forest
tracts. Wilson Bulletin. 105(2): 351-353. [22270]
39. McHugh, Tom. 1958. Social behavior of the American buffalo (Bison
bison). Zoologica. 43(1): 1-40. [3981]
40. Micacchion, Mick; Townsend, T. W. 1983. Botanical characteristics of
autumnal blackbird roosts in central Ohio. Ohio Academy of Sciences.
83(3): 131-135. [5620]
41. Naranjo, Luis G.; Raitt, Ralph J. 1993. Breeding bird distribution in
Chihuahuan Desert habitats. Southwestern Naturalist. 38(1): 43-51.
[20943]
42. Olson, Thomas E.; Gray, M. Violet. 1989. Characteristics of least Bell's
vireo nest sites along the Santa Ynez River. In: Proceedings of the
California riparian systems conference: Protection, management, and
restoration for the 1990's; 1988 September 22-24; Davis, CA. Gen. Tech.
Rep. PSW-110. Berkeley, CA: U.S. Department of Agriculture, Forest
Service, Pacific Southwest Forest and Range Experiment Station: 278-284.
[14447]
43. Raphael, Martin G.; Morrison, Michael L.; Yoder-William, Michael P.
1987. Breeding bird populations during twenty-five years of postfire
succession in the Sierra Nevada. Condor. 89: 614-626. [24941]
44. Robbins, Chandler S.; Bystrak, Danny; Geissler, Paul H. 1986. The
breeding bird survey: its first fifteen years, 1965-1979. Resource
Publication 157. Washington, DC: U.S. Department of the Interior, Fish
and Wildlife Service. 196 p. [24549]
45. Robbins, Chandler S.; Dawson, Deanna K.; Dowell, Barbara A. 1989.
Habitat area requirements of breeding forest birds of the Middle
Atlantic States. Wildlife Monographs. 103: 1-34. [24947]
46. Robinson, Scott K.; Grzybowski, Joseph A.; Rothstein, Stephen I.; [and
others]. 1993. Management implications of cowbird parasitism on
neotropical migrant songbirds. In: Finch, Deborah M.; Stangel, Peter W.,
eds. Status and management of neotropical migratory birds: Proceedings;
1992 September 21-25; Estes Park, CO. Gen. Tech. Rep. RM-229. Fort
Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky
Mountain Forest and Range Experiment Station: 93-102. [1013]
47. Robinson, Scott K.; Thompson, Frank R., III; Donovan, Therese M.; [and
others]. 1995. Regional forest fragmentation and the nesting success of
migratory birds. Science. 267: 1987-1990. [24952]
48. Rodenhouse, Nicholas L.; Best, Louis B.; O'Connor, Raymond J.;
Bollinger, Eric K. 1993. Effects of temperate agriculture on neotropical
migrant landbirds. In: Finch, Deborah M.; Stangel, Peter W., eds. Status
and management of neotropical migratory birds: Proceedings; 1992
September 21-25; Estes Park, CO. Gen. Tech. Rep. RM-229. Fort Collins,
CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain
Forest and Range Experiment Station: 280-295. [23441]
49. Root, Terry L.; Weckstein, Jason D. 1994. Changes in distribution
patterns of select wintering North American birds form 1901 to 1989. In:
Jehl, J. R., Jr.; Johnson, N. K., eds. A century of avifaunal change in
western North America. Studies in Avian Biology. No. 15: 191-201.
[24954]
50. Rothstein, Stephen I. 1994. The cowbird's invasion of the Far West:
history, causes and dadsf consequences experienced by host species. In:
Jehl, J. R., Jr.; Johnson, N. K., eds. A century of avifaunal change in
western North America. Studies in Avian Biology. No. 15: 301-315.
[24955]
51. Rothstein, Stephen I.; Verner, Jared; Stevens, Ernest. 1984.
Radio-tracking confirms a unique diurnal pattern of spatial occurrence
in the parasitic brown-headed cowbird. Ecology. 65(1): 77-88. [24956]
52. Rothstein, Stephen I.; Yokel, David A.; Fleischer, Robert C. 1986.
Social dominance, mating & spacing systems, female fecundity, & social
vocal dialects in captive and free-ranging brown-headed cowbirds. In:
Johnston, Richard F., ed. Current Ornithology. Volume 3. New York:
Plenum Press: 127-185. [24957]
53. Sanders, Susan D.; Flett, Mary Anne. 1989. Montane riparian habitat and
willow flycatchers: threats to a sensitive environment and species. In:
Abell, Dana L., technical coordinator. Proceedings of the California
riparian systems conference: Protection, management, and restoration for
the 1990's; 1988 September 22-24; Davis, CA. Gen. Tech. Rep. PSW-110.
Berkeley, CA:U.S. Department of Agriculture, Forest Service, Pacific
Southwest Forest and Range Experiment Station: 262-266. [14010]
54. Scott, D. M.; Ankney, C. Davidson. 1983. The laying cycle of
brown-headed cowbirds: passerine chickens?. Auk. 100: 583-592. [24946]
55. Sharp, Brian. 1985. Avifaunal changes in central Oregon since 1899.
Western Birds. 16: 63-70. [24940]
56. Shiflet, Thomas N., ed. 1994. Rangeland cover types of the United
States. Denver, CO: Society for Range Management. 152 p. [23362]
57. Sibley, Charles G.; Monroe, Burt L., Jr. 1990. Distribution and taxonomy
of the birds of the world. New Haven, CT: Yale University Press. 1111 p.
[22814]
58. Sieg, Carolyn Hull. 1991. Rocky Mountain juniper woodlands: year-round
avian habitat. Res. Pap. RM-296. Fort Collins, CO: U.S. Department of
Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment
Station. 7 p. [16110]
59. Smith, Charles R.; Pence, Diane M.; O'Connor, Raymond J. 1993. Status of
neotropical migratory birds in the Northeast: a preliminary assessment.
In: Finch, Deborah M.; Stangel, Peter W., eds. Status and management of
neotropical migratory birds: Proceedings; 1992 September 21-25; Estes
Park, CO. Gen. Tech. Rep. RM-229. Fort Collins, CO: U.S. Department of
Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment
Station: 172-188. [17614]
60. Smith, Ronald A.; Hanebrink, Earl L. 1982. Analysis of regurgitated
short-eared owl (Asio flammeus) pellets from the Roth Prairie, Arkansas
County, Arkansas. Arkansas Academy of Science Proceedings. 36: 106-108.
[22376]
61. Stamp, Nancy E. 1978. Breeding birds of riparian woodland in
south-central Arizona. Condor. 80: 64-71. [8079]
62. Stebbins, C. A.; Stebbins, R. C. 1954. [Unknown]. Yosemite Nature Notes.
33(8): 74-152. [14428]
63. Stewart, Robert E.; Kantrud, Harold A. 1972. Population estimates of
breeding birds in North Dakota. Auk. 89: 766-788. [23410]
64. Stewart, Robert E.; Robbins, Chandler S. 1958. Birds of Maryland and the
District of Columbia. North American Fauna: No. 62. Washington, DC: U.S.
Department of the Interior, Fish and Wildlife Service. 401 p. [24044]
65. Terres, John K. 1980. The Audubon Society encyclopedia of North American
birds. New York: Alfred A. Knopf. 1109 p. [16195]
66. Thompson, Frank R.; Lewid, Stephen J.; Green, Janet; Ewert, David. 1993.
Status of neotropical migrant landbirds in the Midwest: identifying
species of management concern. In: Finch, Deborah M.; Stangel, Peter W.,
eds. Status and management of neotropical migratory birds: Proceedings;
1992 September 21-25; Estes Park, CO. Gen. Tech. Rep. RM-229. Fort
Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky
Mountain Forest and Range Experiment Station: 145-158. [21273]
67. U.S. Department of Agriculture, Soil Conservation Service. 1994. Plants
of the U.S.--alphabetical listing. Washington, DC: U.S. Department of
Agriculture, Soil Conservation Service. 954 p. [23104]
68. U.S. Department of the Interior, Fish and Wildlife Service. 1990. Title
50, Code of federal regulations, Part 10: General provisions. FWS/LE
Reg. 10. Washington, DC. 15 p. [23848]
69. Vega, Jorge H.; Rappole, John H. 1994. Composition and phenology of an
avian community in the Rio Grande plain of Texas. Wilson Bulletin.
106(2): 366-380. [23933]
70. Verner, Jared; Ritter, Lyman V. 1983. Current status of the brown-headed
cowbird in the Sierra National Forest. Auk. 100: 355-368. [24958]
71. Wirtz, William O., II. 1991. Avifauna in southern California chaparral:
seasonal distribution, habitat association, reproductive phenology. Res.
Pap. PSW-RP-209. Berkeley, CA: U.S. Department of Agriculture, Forest
Service, Pacific Southwest Research Station. 19 p. [23431]
72. Yahner, Richard H. 1987. Use of even-aged stands by winter and spring
bird communities. Wilson Bulletin. 99(2): 218-232. [24959]
73. Friedmann, Herbert; Kiff, Lloyd F. 1985. The parasitic cowbirds and
their hosts. Proceedings of the Western Foundation of Vertebrate
Zoology. 2: 226-304. [24950]
74. Biological Advisory Team. 1990. Comprehensive report of the Biological
Advisory Team for the Balcones Canyonlands Habitat Conservation Plan.
Austin, TX: City of Austin, Environmental Division. 80 p. Unpublished
report. [27372]
75. Carter, Michael F.; Barker, Keith. 1993. An interactive database for
setting conservation priorities for western neotropical migrants. In:
Finch, Deborah M.; Stangel, Peter W., eds. Status and management of
neotropical migratory birds: Proceedings; 1992 September 21-25; Estes
Park, CO. Gen. Tech. Rep. RM-229. Fort Collins, CO: U.S. Department of
Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment
Station: 120-144. [16259]
76. Kline, Patricia; Broersma, Klaas; Wright, Scott B. M.; Rode, Lyle M.
1993. Meadow foxtail: A production guide. Publication 1890/E. Ottawa,
ON: Agriculture Canada. 23 p. [26080]
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