Index of Species Information
WILDLIFE SPECIES: Brachylagus idahoensis
Introductory
WILDLIFE SPECIES: Brachylagus idahoensis
AUTHORSHIP AND CITATION :
Tesky, Julie L. 1994. Brachylagus idahoensis. 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/mammal/brid/all.html [].
ABBREVIATION :
BRID
COMMON NAMES :
pygmy rabbit
Columbia Basin pygy rabbit
TAXONOMY :
The currently accepted scientific name for the pygmy rabbit is
Brachylagus idahoensis (Merriam) [8]. Some authorities have placed the
pygmy rabbit in the genus Sylvilagus subgenus Brachylagus [9,14]. Pygmy
rabbits are in the family Leporidae [8].
ORDER :
Lagomorpha
CLASS :
Mammal
FEDERAL LEGAL STATUS :
Populations in Douglas, Grant, Lincoln, Adams, and Benton counties, Washington,
are listed as Endangered [25].
OTHER STATUS :
Information on state- and province-level protection status of animals in the
United States and Canada is available at NatureServe, although recent changes
in status may not be included.
WILDLIFE DISTRIBUTION AND OCCURRENCE
WILDLIFE SPECIES: Brachylagus idahoensis
GENERAL DISTRIBUTION :
The range of the pygmy rabbit includes most of the Great Basin and some
of the adjacent intermountain areas of the western United States [8].
Pygmy rabbits are found in southwestern Montana from the extreme
southwest corner near the Idaho border north to Dillon and Bannack in
Beaverhead County [4]. Distribution continues east to southern Idaho
and southern Oregon and south to northern Utah, northern Nevada, and
eastern California. Isolated populations occur in east-central
Washington [2] and Wyoming [21].
The elevational range of pygmy rabbits in Nevada extends from 4,494 to
over 7,004 feet (1,370-2,135 m) and in California from 4,986 to 5,298
feet (1,520-1,615 m) [8].
ECOSYSTEMS :
FRES29 Sagebrush
FRES30 Desert shrub
STATES :
BLM PHYSIOGRAPHIC REGIONS :
2 Cascade Mountains
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
KUCHLER PLANT ASSOCIATIONS :
K038 Great Basin sagebrush
K040 Saltbush - greasewood
K055 Sagebrush steppe
K056 Wheatgrass - needlegrass shrubsteppe
SAF COVER TYPES :
NO-ENTRY
SRM (RANGELAND) COVER TYPES :
NO-ENTRY
PLANT COMMUNITIES :
Pygmy rabbits are found primarily in big sagebrush (Artemisia
tridentata) and rabbitbrush (Chrysothamnus spp.) dominated communities
[2,7,16,18]. Pygmy rabbits are also found in areas where greasewood
(Sarcobatus spp.) is abundant [7]. Some woody species found on sites
inhabited by pygmy rabbits in southeastern Idaho include big sagebrush,
antelope bitterbrush (Purshia tridentata), threetip sagebrush (A.
tripartita), low rabbitbrush (C. viscidiflorus), gray horsebrush
(Tetradymia canescens), and prickly phlox (Leptodactylon pungens).
Grasses and forbs include thick spike wheatgrass (Elymus lanceolatus),
plains reedgrass (Calamagrostis montanensis), sedges (Carex spp.),
prairie junegrass (Koeleria macrantha), Sandberg bluegrass (Poa
secunda), bluegrass (Poa spp.), needle-and-thread grass (Stipa comata),
western yarrow (Achillea millefolium), rosy pussytoes (Antennaria
microphylla), milkvetch (Astragalus spp.), arrowleaf balsamroot
(Balsamorhiza sagittata), buckwheat (Eriogonum spp.), tailcup lupine
(Lupinus caudatus), and phlox (Phlox spp.) [7]. In the Upper Sonoran
Desert pygmy rabbits occur in desert sagebrush associations dominated by
big sagebrush and rabbitbrush with bitterbrush and sulphurflower
(Eriogonum umbellatum var. stellatum) [16].
BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Brachylagus idahoensis
TIMING OF MAJOR LIFE HISTORY EVENTS :
Age at sexual maturity - Pygmy rabbits are capable of breeding when they
are about 1 year old [8,20].
Breeding season - The breeding season of pygmy rabbits is very short.
In Idaho it lasts from March through May; in Utah, from February through
March [22].
Gestation period and litter size - The gestation period of pygmy rabbits
is unknown. It is between 27 and 30 days in various species of
cottontails (Sylvilagus spp.). An average of six young are born per
litter and a maximum of three litters are produced per year [8]. In
Idaho the third litter is generally produced in June [20]. It is
unlikely that litters are produced in the fall [8].
Growth rate of juveniles - The growth rates of juveniles are dependent
on the date of birth. Young from early litters grow larger due to a
longer developmental period prior to their first winter [8].
Mortality - The mortality of adults is highest in late winter and early
spring. Green and Flinders [8] reported a maximum estimated annual
adult mortality of 88 percent in Idaho. Juvenile mortality was highest
from birth to 5 weeks of age [8].
Pygmy rabbits may be active at any time of day; however, they are
generally most active at dusk and dawn. They usually rest near or
inside their burrows during midday [8].
PREFERRED HABITAT :
Pygmy rabbits are generally limited to areas on deep soils with tall,
dense sagebrush which they use for cover and food [4,8]. Individual
sagebrush plants in areas inhabited by pygmy rabbits are often 6 feet
(1.8 m) or more in height [4]. Extensive, well-used runways interlace
the sage thickets and provide travel and escape routes [8]. Dense
stands of big sagebrush along streams, roads, and fencerows provide
dispersal corridors for pygmy rabbits [17].
Burrows - The pygmy rabbit is the only native leporid that digs burrows.
Juveniles use burrows more than other age groups. Early reproductive
activities of adults may be concentrated at burrows [8]. When pygmy
rabbits can utilize sagebrush cover, burrow use is decreased. Pygmy
rabbits use burrows more in the winter for thermal cover than at other
times of the year [20].
Burrows are usually located on slopes at the base of sagebrush plants,
and face north to east. Tunnels widen below the surface, forming
chambers, and extend to a maximum depth of about 3.3 feet (1 m).
Burrows typically have 4 or 5 entrances but may have as few as 2 or as
many as 10 [8]. In Oregon, pygmy rabbits inhabited areas where soils
were significantly deeper and looser than soils at adjacent sites. Site
selection was probably related to ease of excavation of burrows [17].
In areas where soil is shallow pygmy rabbits live in holes among
volcanic rocks, in stone walls, around abandoned buildings, and in
burrows made by badgers (Taxidea taxus) and marmots (Marmota
flaviventris) [2,8].
Some researchers have found that pygmy rabbits never venture further
than 60 feet (21.3 m) from their burrows [2]. However, Bradfield [2]
observed pygmy rabbits range up to 328 feet (100 m) from their burrows.
Winter - Some areas inhabited by pygmy rabbits are covered with several
feet of snow for up to 2 or more months during the winter. During
periods when the snow has covered most of the sagebrush, pygmy rabbits
tunnel beneath the snow to find food. Snow tunnels are approximately
the same height and width as underground burrows. They are quite
extensive and extend from one sagebrush to another [2,8]. Aboveground
movement during the winter months is restricted to these tunnel systems
[2].
COVER REQUIREMENTS :
Pygmy rabbits are restricted to areas with heavy shrub cover [4,8].
Pygmy rabbits are seldom found in areas of sparse vegetative cover and
seem to be reluctant to cross open space [2]. In southeastern Idaho,
woody cover and shrub heights were significantly (P<0.01) greater on
sites occupied by pygmy rabbits than on other sites in the same area
[7].
FOOD HABITS :
The primary food of pygmy rabbits is big sagebrush, which may comprise
up to 99 percent of the food eaten in the winter. Grasses and forbs are
also eaten from mid- to late summer [2,6,7,8]. In Idaho, Gates and Eng
[6] found that shrubs contributed 85.2 percent (unweighted mean) of
pygmy rabbit diets from July to December. Shrub use was lowest in
August (73.1%) and highest in December (97.9%). Big sagebrush was the
most important shrub in the July to December diet (54.2%), followed by
rubber rabbitbrush (Chrysothamnus nauseosus) (25.8%) and winterfat
(Krascheninnikovia lananta) (4.6%). Grasses comprised 10 percent of the
July to December diet and were consumed mostly during July and August.
Indian ricegrass (Oryzopsis hymenoides) and needlegrass (Stipa spp.)
were the most important grasses consumed. Forbs contributed 4.9 percent
of the July to December diet [6].
In southeastern Idaho, Green and Flinders [7] found that pygmy rabbits
ate big sagebrush throughout the year but in lesser amounts in summer
(51% of diet) than in winter (99% of diet). Other shrubs in the area
were consumed infrequently. Grass and forb consumption was relatively
constant throughout the summer (39% and 10% of diet respectively) and
decreased to a trace amount through fall and winter. Thickspike
wheatgrass, bluebunch wheatgrass (Pseudoroegneria spicata), and Sandberg
bluegrass were preferred foods in the summer [7].
PREDATORS :
Weasels (Mustela spp.) are the principal predators of pygmy rabbits.
Coyote (Canis latrans), red fox (Vulpes vulpes), badger, bobcat (Felis
rufus), great horned owl (Bubo virginianus) and marsh hawk (Circus
cyaneus) also prey on pygmy rabbits [2,8,20].
MANAGEMENT CONSIDERATIONS :
Some populations of pygmy rabbits are susceptible to rapid declines and
possibly local extirpation. Some studies suggest that pygmy rabbits are
a "high inertia" species with low capacity for rapid increase in density
[17]. The loss of habitat is probably the most significant factor
contributing to pygmy rabbit population declines. Sagebrush cover is
critical to pygmy rabbits and sagebrush eradication is detrimental [10].
Protection of sagebrush, particularly on floodplains and where high
water tables allow growth of tall, dense stands, is vital to the
survival of pygmy rabbits [4]. Fragmentation of sagebrush communities
also poses a threat to populations of pygmy rabbits [17] because
dispersal potential is limited.
FIRE EFFECTS AND USE
WILDLIFE SPECIES: Brachylagus idahoensis
DIRECT FIRE EFFECTS ON ANIMALS :
Pygmy rabbits probably are capable of escaping slow moving fires;
however, they may be burned or die of asphyxiation in some fires.
During a prescribed burn of a big sagebrush-grassland community in
Idaho, several pygmy rabbits died in an area where the fire advanced
rapidly. Although pygmy rabbits use burrows, the burrows evidently do
not always provide them with effective protection from fire [6].
HABITAT RELATED FIRE EFFECTS :
Loss of big sagebrush as a result of a fire may decrease both food and
cover for pygmy rabbits. Big sagebrush is often completely killed by
fire and is slow to reestablish on burned sites. On the Upper Snake
River Plains in Idaho, big sagebrush did not recover to prefire
densities until 30 years after an August fire [23]. Big sagebrush may
be eliminated from some areas due to repeated fire [24]. Fires that
eliminate much of the big sagebrush would have an adverse effect on the
pygmy rabbit population in that area. Two months following an August
prescribed fire in a big sagebrush-grassland community in Idaho, only 3
of 11 located radio-collared pygmy rabbits were still alive. Predation
was a cause of death for seven of the eight pygmy rabbits. The loss of
big sagebrush cover from their home ranges probably increased their
vulnerability to predation. Some of the surviving pygmy rabbits
abandoned their home ranges and established new home ranges on adjacent
unburned sites. Of the six pygmy rabbits that remained on the burn
site, only one survived through winter [6].
FIRE USE :
Burned areas can be reseeded and planted with big sagebrush to help
facilitate sagebrush establishment. Seeding on 4 to 8 inches (10-20 cm)
of snow is a successful way to establish seedlings. Aerial seeding of
big sagebrush in the late fall is suitable for sites where planting seed
to is not practical. Areas planted or seeded with big sagebrush should
be protected from livestock grazing for several years [12].
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
WILDLIFE SPECIES: Brachylagus idahoensis
REFERENCES :
1. 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]
2. Bradfield, Terry D. 1975. Aon the behavior and ecology of the pygmy
rabbit. Pocatello, ID: Idaho State University. 43 p. Thesis. [23639]
3. Eyre, F. H., ed. 1980. Forest cover types of the United States and
Canada. Washington, DC: Society of American Foresters. 148 p. [905]
4. Flath, Dennis. 1994. Bunnies by the bunch. Montana Outdoors. 25(3):
8-13. [23637]
5. 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]
6. Gates, Robert J.; Eng, Robert L. 1984. Sage grouse, pronghorn, and
lagomorph use of a sagebrush-grassland burn site on the Idaho National
Engineering Laboratory. In: Markham, O. Doyle, ed. Idaho National
Engineering Laboratory radio ecology and ecology programs: 1983 progress
reports. Idaho Falls, ID: U.S. Department of Energy, Radiological and
Environmental Sciences Laboratory: 220-235. [1005]
7. Green, Jeffery, S.; Flinders, Jerran T. 1980. Habitat and dietary
relationships of the pygmy rabbit. Journal of Range Management. 33(2):
136-142. [6257]
8. Green, Jeffrey S.; Flinders, Jerran T. 1980. Brachylagus idahoensis.
Mammalian Species. 125: 1-4. [23631]
9. Hall, E. Raymond; Kelson, Keith R. 1959. The mammals of North America,
Volume II. New York: The Ronald Press Company. 79 p. [21460]
10. Holechek, Jerry L. 1981. Brush control impacts on rangeland wildlife.
Journal of Soil and Water Conservation. 36(5): 265-269. [1182]
11. Jones, Fred L. 1957. Southern extension of the range of the pigmy rabbit
in California. Journal of Mammalogy. 38(2): 274. [23632]
12. Klott, James H.; Ketchum, Chris. 1991. The results of using "Hobble
Creek" sagebrush on two fire rehabilitations. Idaho BLM Technical
Bulletin 91-1. Boise, ID: U.S. Department of the Interior, Bureau of
Land Management. 12 p. [19869]
13. 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]
14. Orr, R. T. 1940. The rabbits of California. Occassional Papers of the
California Academy of Sciences. 19: 1-227. [23641]
15. Pritchett, C. L.; Nilsen, J. A.; Coffeen, M. P.; Smith, H. D. 1987.
Pygmy rabbits in the Colorado River drainage. Great Basin Naturalist.
47(2): 231-233. [23633]
16. Severaid, Joye Harold. 1950. The pigmy rabbit (Sylvilagus idahoensis) in
Mono County, California. Journal of Mammalogy. 31(1): 1-4. [23634]
17. Weiss, Nondor T.; Verts, B. J. 1984. Habitat and distribution of pygmy
rabbits (Sylvilagus idahoensis) in Oregon. Great Basin Naturalist.
44(4): 563-571. [23635]
18. Welch, Bruce L.; Wagstaff, Fred J.; Roberson, Jay A. 1991. Preference of
wintering sage grouse for big sagebrush. Journal of Range Management.
44(5): 462-465. [16608]
19. White, Susan M.; Flinders, Jerran T.; Welch, Bruce L. 1982. Preference
of pygmy rabbits (Brachylagus idahoensis) for various populations of big
sagebrush (Artemisia tridentata). Journal of Range Management. 35(6):
724-726. [23636]
20. Wilde, Douglas B.; Keller, Barry L. 1978. An analysis of pygmy rabbit
populations on the Idaho National Engineering Laboratory site. In:
Markham, O. D., ed. Ecological studies on the Idaho National Engineering
Laboratory site. 1978 Progress Report IDO-12087. Idaho Falls, ID: U.S.
Department of Energy, Environmental Sciences Branch, Radiological and
Environmental Sciences Lab: 305-316. [2561]
21. Campbell, Thomas M., III; Clark, Tim W.; Groves, Craig R. 1982. Firest
record of pygmy rabbits (Brachylagus idahoensis) in Wyoming. Great Basin
Naturalist. 42(1): 100. [23638]
22. Chapman, Joseph A.; Feldhamer, George A., eds. 1982. Wild mammals of
North America. Baltimore, MD: The Johns Hopkins University Press. 1147
p. [21085]
23. Harniss, Roy O.; Murray, Robert B. 1973. 30 years of vegetal change
following burning of sagebrush-grass range. Journal of Range Management.
26(5): 322-325. [1086]
24. Rosentreter, Roger; Jorgensen, Ray. 1986. Restoring winter game ranges
in southern Idaho. Tech. Bull. 86-3. Boise, ID: U.S. Department of the
Interior, Bureau of Land Management, Idaho State Office. 26 p. [5295]
25. U.S. Department of the Interior, Fish and Wildlife Service. 2016.
Endangered Species Program, [Online]. Available: http://www.fws.gov/endangered/.
[86564]
26. Washington Department of Wildlife. 1994. Species of special concern in
Washington - state and federal status. Olympia, WA: Washington
Department of Wildlife. 41 p. [25414]
FEIS Home Page
https://www.fs.usda.gov/database/feis/animals/mammal/brid/all.html
