Pygmy rabbit

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Pygmy rabbit [1]
BRACHYLAGUS IDAHOENSIS.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Lagomorpha
Family: Leporidae
Genus: Brachylagus
Species:
B. idahoensis
Binomial name
Brachylagus idahoensis
(Merriam, 1891)
Pygmy Rabbit area.png
Pygmy rabbit range
(blue – native, pink – reintroduced)
Synonyms

Lepus idahoensis Merriam, 1891 [3] Lepus (Brachylagus) idahoensis [4] Microlagus idahoensis [1]
Sylvilagus idahoensis [1]

Contents

The pygmy rabbit (Brachylagus idahoensis) is a rabbit species native to the United States. It is also the only native rabbit species in North America to dig its own burrow. [5] [6] The pygmy rabbit differs significantly from species within either the Lepus (hare) or Sylvilagus (cottontail) genera and is generally considered to be within the monotypic genus Brachylagus. One isolated population, the Columbia Basin pygmy rabbit, is listed as an endangered species by the U.S. Federal government, though the International Union for Conservation of Nature lists the species as lower risk.

Taxonomy

The pygmy rabbit was first described by Clinton Hart Merriam in 1891, as Lepus idahoensis; the type specimen, in winter pelage, had been collected in the Pahsimeroi Valley the previous autumn. [3] In 1900, Gerrit S. Miller, Jr. erected the new subgenus Brachylagus for the pygmy rabbit; [4] Brachylagus has since been elevated to the rank of genus. [1] Historically, the pygmy rabbit has also been placed in the genera Microlagus and Sylvilagus . [1]

Description

The pygmy rabbit is the world's smallest leporid, [7] [8] [9] [10] with adults weighing between 375 and 500 grams (0.827 and 1.102 lb), and having a body length between 23.5 and 29.5 centimeters (9.3 and 11.6 in); females are slightly larger than males. The pygmy rabbit is distinguishable from other leporids by its small size, short ears, gray color, small hind legs, and lack of white fuzzy fur.

Distribution

The range of the pygmy rabbit includes most of the Great Basin and some of the adjacent intermountain areas of western North America. [11] Pygmy rabbits are found in southwestern Montana from the extreme southwest corner near the Idaho border north to Dillon and Bannack in Beaverhead County. [12] Distribution continues west to southern Idaho and southern Oregon, and south to northern Utah, northern Nevada, and north-eastern California. An isolated population occurs in east-central Washington, [13] and another in Wyoming. [14]

The elevational range of pygmy rabbits in Nevada extends from 1,370–2,135 meters (4,495–7,005 ft) and in California from 1,520–1,615 meters (4,987–5,299 ft). [11]

The last male purebred Columbia Basin pygmy rabbit, found only in the Columbia Basin of Washington state, died 30 March 2006, at the Oregon Zoo in Portland. The last purebred female died in 2008. [15] A crossbreeding program conducted by the Oregon Zoo, Washington State University, and Northwest Trek is attempting to preserve the genetic line by breeding surviving females with the Idaho pygmy rabbit. [16]

Lifecycle

Pygmy rabbits are capable of breeding when they are about 1 year old. [11] [17]

The breeding season of pygmy rabbits is very short. In Idaho it lasts from March through May; in Utah, from February through March. [18] 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. [11] In Idaho the third litter is generally produced in June. [17] It is unlikely that litters are produced in the fall. [11]

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. [11]

The mortality of adults is highest in late winter and early spring. Green & Flinders (1980) [11] reported a maximum estimated annual adult mortality of 88% in Idaho. Juvenile mortality was highest from birth to 5 weeks of age. [11]

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. [11]

Habitat

Pygmy rabbits are normally found in areas on deep soils with tall, dense sagebrush which they use for shelter and food. [11] [12] Individual sagebrush plants in areas inhabited by pygmy rabbits are often 6 feet (1.8 m) or more in height. [12] Extensive, well-used runways interlace the sage thickets and provide travel and escape routes. [11] Dense stands of big sagebrush along streams, roads, and fencerows provide dispersal corridors for pygmy rabbits. [19]

The pygmy rabbit is the only leporid native to North America that digs burrows. [5] [6] Juveniles use burrows more than other age groups. Early reproductive activities of adults may be concentrated at burrows. [11] 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. [17]

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 1 meter (3.3 ft). Burrows typically have 4 or 5 entrances but may have as few as 2 or as many as 10. [11] 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. [19] 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). [11] [13]

Some researchers have found that pygmy rabbits never venture farther than 60 feet (18 m) from their burrows. [13] However, Bradfield [13] observed pygmy rabbits range up to 100 meters (330 ft) from their burrows.

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 burrows. They are quite extensive and extend from one sagebrush to another. [11] [13] Above ground movement during the winter months is restricted to these tunnel systems. [13]

Cover requirements

Pygmy rabbits are restricted to areas with heavy shrub cover. [11] [12] Pygmy rabbits are seldom found in areas of sparse vegetative cover and seem to be reluctant to cross open space. [13] In southeastern Idaho, woody cover and shrub height were significantly (p < 0.01) greater on sites occupied by pygmy rabbits than on other sites in the same area. [20]

Plant communities

Pygmy rabbits are found primarily in big sagebrush ( Artemisia tridentata ) and rabbitbrush ( Chrysothamnus spp.) dominated communities. [13] [21] [20] [22] [23] Pygmy rabbits are also found in areas where greasewood ( Sarcobatus spp.) is abundant. [20] 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.). [20] 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). [22]

Food habits

The primary food of pygmy rabbits is big sagebrush, which may comprise up to 99% of the food eaten in the winter. Grasses and forbs are also eaten from mid- to late summer. [11] [13] [20] [24] In Idaho, Gates & Eng (1984) [24] found that shrubs contributed 85.2% (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 lanata , 4.6%). Grasses comprised 10% 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% of the July to December diet. [24]

In southeastern Idaho, Green & Flinders (1980) [20] 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. [20]

Predators

Weasels ( Mustela and Neogale spp.) are the principal predators of pygmy rabbits. Coyotes ( Canis latrans ), red foxes ( Vulpes vulpes ), American badgers ( Taxidea taxus ), bobcats ( Lynx rufus ), great horned owls ( Bubo virginianus ), and northern harriers ( Circus hudsonius ) also prey on pygmy rabbits. [11] [13] [17]

Listing status

In September 2007, Judge Edward Lodge [25] of the U.S. District Court granted summary judgment to Western Watersheds Project, the litigant party, remanding the United States Fish and Wildlife Service 90 day finding denying conservationist parties' listing petition. The petition sought legal protection for pygmy rabbit as an endangered or threatened species. [25]

Related Research Articles

<span class="mw-page-title-main">Leporidae</span> Family of lagomorphs

Leporidae is the family of rabbits and hares, containing over 70 species of extant mammals in all. The Latin word Leporidae means "those that resemble lepus" (hare). Together with the pikas, the Leporidae constitute the mammalian order Lagomorpha. Leporidae differ from pikas in that they have short, furry tails and elongated ears and hind legs.

<span class="mw-page-title-main">Snowshoe hare</span> Species of mammal

The snowshoe hare, also called the varying hare or snowshoe rabbit, is a species of hare found in North America. It has the name "snowshoe" because of the large size of its hind feet. The animal's feet prevent it from sinking into the snow when it hops and walks. Its feet also have fur on the soles to protect it from freezing temperatures.

<span class="mw-page-title-main">Greater sage-grouse</span> Species of bird

The greater sage-grouse, also known as the sagehen, is the largest grouse in North America. Its range is sagebrush country in the western United States and southern Alberta and Saskatchewan, Canada. It was known as simply the sage grouse until the Gunnison sage-grouse was recognized as a separate species in 2000. The Mono Basin population of sage grouse may also be distinct.

<span class="mw-page-title-main">Desert cottontail</span> Species of mammal

The desert cottontail, also known as Audubon's cottontail, is a New World cottontail rabbit, and a member of the family Leporidae. Unlike the European rabbit, they do not form social burrow systems, but compared with some other leporids, they are extremely tolerant of other individuals in their vicinity.

<span class="mw-page-title-main">Cottontail rabbit</span> Genus of mammals

Cottontail rabbits are in the Sylvilagus genus, which is in the Leporidae family. They are found in the Americas. Most Sylvilagus species have stub tails with white undersides that show when they retreat, giving them their characteristic name. However, this feature is not present in all Sylvilagus, nor is it unique to the genus.

<span class="mw-page-title-main">Eastern cottontail</span> Species of mammal

The eastern cottontail is a New World cottontail rabbit, a member of the family Leporidae. It is the most common rabbit species in North America.

<span class="mw-page-title-main">Sagebrush steppe</span> Grassland ecosystem

Sagebrush steppe also known as the sagebrush sea, is a type of shrub-steppe, a plant community characterized by the presence of shrubs, and usually dominated by sagebrush, any of several species in the genus Artemisia. This ecosystem is found in the Intermountain West in the United States.

<i>Brachylagus</i> Genus of mammals

Brachylagus is a genus of lagomorph that contains the smallest living leporid, the pygmy rabbit. One extinct species, Brachylagus coloradoensis, is also known.

<span class="mw-page-title-main">Ord's kangaroo rat</span> Species of rodent

Ord's kangaroo rat is a kangaroo rat native to western North America, specifically the Great Plains and the Great Basin, with its range extending from extreme southern Canada to central Mexico.

<span class="mw-page-title-main">Great Basin pocket mouse</span> Species of rodent

The Great Basin pocket mouse is a species of rodent in the family Heteromyidae. It is found in British Columbia in Canada and the western United States.

<span class="mw-page-title-main">Mexican cottontail</span> Species of mammal

The Mexicаn cottontail is a species of cottontail rabbit in the family Leporidae. It is endemic to Mexico where its natural habitats are temperate forests, subtropical or tropical dry forests and pastureland.

<span class="mw-page-title-main">Mountain cottontail</span> Species of mammal

The mountain cottontail or Nuttall's cottontail is a species of mammal in the family Leporidae. It is found in Canada and the United States.

<span class="mw-page-title-main">Snake River Plain (ecoregion)</span> Ecoregion in the northwestern United States

The Snake River Plain ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the U.S. states of Idaho and Oregon. It follows the Snake River across Idaho, stretching roughly 400 miles (640 km) from the Wyoming border to Eastern Oregon in the xeric intermontane west. Characterized by plains and low hills, it is considerably lower and less rugged than surrounding ecoregions. Many of the alluvial valleys bordering the Snake River are used for agriculture. Where irrigation water and soil depth are sufficient, sugar beets, potatoes, alfalfa, small grains, and vegetables are grown. Elsewhere, livestock grazing is widespread. Cattle feedlots and dairy operations are found locally.

<span class="mw-page-title-main">Northern Basin and Range ecoregion</span>

The Northern Basin and Range ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the U.S. states of Oregon, Idaho, Nevada, Utah, and California. It contains dissected lava plains, rolling hills, alluvial fans, valleys, and scattered mountain ranges in the northern part of the Great Basin. Although arid, the ecoregion is higher and cooler than the Snake River Plain to the north and has more available moisture and a cooler climate than the Central Basin and Range to the south. Its southern boundary is determined by the highest shoreline of Pleistocene Lake Bonneville, which once inundated the Central Basin and Range. The western part of the region is internally drained; its eastern stream network drains to the Snake River system.

<span class="mw-page-title-main">Black-tailed jackrabbit</span> Common hare of the western United States and Mexico

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<span class="mw-page-title-main">Lost Forest Research Natural Area</span> Protected area in the United States

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<span class="mw-page-title-main">Columbia Basin pygmy rabbit</span>

The Columbia Basin pygmy rabbit is an isolated population of pygmy rabbit that is native only to a single Columbia Basin area of Washington state. The Columbia Basin pygmy rabbit is the smallest North American rabbit. While the IUCN considers the species as a whole to be of least concern, the US Fish & Wildlife Service considers this a distinct population segment, and thus merits protections under the Endangered Species Act. The last purebred Columbia Basin pygmy rabbit died in 2008, marking the end of the pure genetic line.

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References

  1. 1 2 3 4 5 Hoffman, R.S.; Smith, A.T. (2005). "Order Lagomorpha". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 194. ISBN   978-0-8018-8221-0. OCLC   62265494.
  2. ↑ Rachlow, J.; Becker, P.A.; Shipley, L. (2016). "Brachylagus idahoensis". IUCN Red List of Threatened Species . 2016: e.T2963A45176206. doi: 10.2305/IUCN.UK.2016-3.RLTS.T2963A45176206.en . Retrieved 19 November 2021.
  3. 1 2 Merriam, C. Hart (1891). "Results of a Biological Reconnoissance of south-central Idaho". North American Fauna . 5: 76–78.
  4. 1 2 Miller, Gerrit S., Jr. (1900). "General Notes: A new subgenus for Lepus idahoensis". Proceedings of the Biological Society of Washington . 13: 157.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. 1 2 Silberstein, Maya. "Leporidae (hares and rabbits)". Animal Diversity Web. Retrieved 2020-08-21.
  6. 1 2 "Pygmy rabbit". www.fws.gov. Retrieved 2020-08-21.
  7. ↑ Goodwin, George Gilbert; Drimmer, Frederick (1954). The Animal kingdom: the strange and wonderful ways of mammals, birds, reptiles, fishes, and insects; a new and authentic natural history of the wildlife of the world. Vol. 1. Cornell University. p. 246. ASIN   B09SHGMG2M.
  8. ↑ Goodwin, George C. (1962). Small mammals. Cornell University.
  9. ↑ Sharth, Sharon (1999). Rabbits . Child's World. p.  12. ISBN   156766587X.
  10. ↑ Meet the World's Smallest Rabbit, October 14, 2009
  11. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Green, Jeffrey S.; Flinders, Jerran T. (1980). "Brachylagus idahoensis". Mammalian Species (125): 1–4. doi: 10.2307/3503856 . JSTOR   3503856.
  12. 1 2 3 4 Flath, Dennis. 1994. Bunnies by the bunch. Montana Outdoors. 25(3): 8–13.
  13. 1 2 3 4 5 6 7 8 9 10 Bradfield, Terry D. (1975). On the behavior and ecology of the pygmy rabbit (Thesis). Pocatello, ID: Idaho State University.
  14. ↑ Campbell, Thomas M.; Clark, Tim W.; Groves, Craig R. (1982). "First record of pygmy rabbits (Brachylagus idahoensis) in Wyoming". Great Basin Naturalist. 42 (1): 100.
  15. ↑ "Editor's Note". National Geographic Magazine . January 2009. Archived from the original on 2009-02-01 – via ngm.typepad.com.
  16. ↑ Wiley, John K. (13 May 2007). "Captive breeding offers hope for near-extinct pygmy rabbits". The Seattle Times . Associated Press . Retrieved 1 July 2022.
  17. 1 2 3 4 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 (Report). Environmental Sciences Branch / Radiological and Environmental Sciences Laboratory. Idaho Falls, ID: U.S. Department of Energy / Idaho National Engineering Laboratory. pp. 305–316. OSTI   6139364. IDO-12087.
  18. ↑ Chapman, Joseph A.; Feldhamer, George A., eds. (1982). Wild mammals of North America. Baltimore, MD: The Johns Hopkins University Press.
  19. 1 2 Weiss, Nondor T.; Verts, B. J. (1984). "Habitat and distribution of pygmy rabbits (Sylvilagus idahoensis) in Oregon". Great Basin Naturalist. 44 (4): 563–571. JSTOR   41712112.
  20. 1 2 3 4 5 6 7 Green, Jeffery S.; Flinders, Jerran T. (1980). "Habitat and dietary relationships of the pygmy rabbit". Journal of Range Management. 33 (2): 136–142. doi:10.2307/3898429. hdl: 10150/646516 . JSTOR   3898429.
  21. ↑ Larrucea, Eveline S.; Brussard, Peter F. (2008). "Habitat selection and current distribution of the pygmy rabbit in Nevada and California, USA". Journal of Mammalogy. 89 (3): 691–699. doi:10.1644/07-MAMM-A-199R.1. S2CID   55487275.
  22. 1 2 Severaid, Joye Harold (1950). "The pigmy rabbit (Sylvilagus idahoensis) in Mono County, California". Journal of Mammalogy. 31 (1): 1–4. doi:10.2307/1375469. JSTOR   1375469.
  23. ↑ 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. doi:10.2307/4002745. hdl: 10150/644764 . JSTOR   4002745.
  24. 1 2 3 Gates, Robert J.; Eng, Robert L. (1984). "Radio Ecology and Ecology Programs 1983 Progress Reports". In Markham, O. Doyle (ed.). Sage grouse, pronghorn, and lagomorph use of a sagebrush-grassland burn site on the Idaho National Engineering Laboratory (Report). Idaho National Engineering Laboratory. Idaho Falls, ID: U.S. Department of Energy / Radiological and Environmental Sciences Laboratory. pp. 220–235.
  25. 1 2 Lodge, E. (26 September 2007). Standard for listing petitions & evaluation of threats to the pygmy rabbit (PDF) (Report). United States District Court for the District of Idaho. Archived from the original (PDF) on 4 January 2011. Retrieved 26 September 2007.

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