Idaho ground squirrel
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Idaho ground squirrel ( Urocitellus brunneus ) |
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| ( AH Howell , 1928) |
The Idaho ground squirrel ( Urocitellus brunneus , syn .: Spermophilus brunneus ) is a species of squirrel from the genus Urocitellus . It is endemic to the west of the American state of Idaho .
features
The Idaho ground squirrel reaches a head-torso length of about 17.3 to 18.3 centimeters, the tail is about 55 millimeters long and is thus significantly shorter than the rest of the body. The weight is 110 to 210 grams, with the males about 2.5 to 3.3% larger and heavier than the females. The animals have a comparatively small body and head as well as a short tail, their backs are brown with clear white spots. The nose, legs and belly are yellowish pink to orange in color. A white eye ring is noticeable. Compared to the Townsend ground squirrel ( Urocitellus townsendi ) and the Washington ground squirrel ( Urocitellus washingtoni ), the animals are darker in color and the spots are more conspicuous, but both species have more conspicuous side lines.
distribution
The Idaho ground squirrel is endemic to the American state of Idaho . The distribution area is limited to three isolated occurrences: One north of the Payette River to the Cuddy Mountains and the Hill Mountains , one between the Seven Devils Mountains and the Cuddy Mountains and one east of the West Mountains . Even within these distribution areas, the populations are partially separated (disjoint).
Way of life
The Idaho ground squirrel is diurnal and lives mainly in pastures and meadows with grasses and herbs as the dominant vegetation. In the northern part of the distribution area it also occurs in open conifer stands with a dense undergrowth of herbs and grasses.
It is primarily herbivorous and, like other ground squirrels, its diet consists mainly of different parts of plants such as grasses, buds, flowers, sprouts, leaves and roots as well as seeds, and occasionally insects and fungi. The animals live like other ground squirrels on the ground and in underground burrows. They use different types of construction for rearing the young, for wintering and as escape structures in the event of threat. The animals hibernate from early August to late March, whereby the individual individuals of the more northerly subspecies Urocitellus brunneus brunneus are usually not active above ground for more than four months per year.
The males leave their burrows in spring about two weeks before the females. In the first two days after the appearance of the females it comes to the area forming the males and mating . The males then guard the females from other males, especially when the density and number of females is low. Stronger males can displace weaker males and take over females; according to genetic studies, 66 to 100% of the last and longest guarded males are also the fathers of the young animals. Mating takes place underground and the males produce Begattungspfropfen that the vagina close to the females. On average, a litter consists of four to six young animals. These leave the burrow together in March or early April at Urocitellus brunneus endemicus and about four weeks later at Urocitellus brunneus brunneus .
In parts of the distribution area there is competition with the Columbia ground squirrel ( Urocitellus columbianus ) for suitable habitats and burrows. The main predators of the Idaho Ground Squirrel is silver badgers ( Taxidea taxus ) and long-tailed weasel ( Mustela frenata ) and various birds of prey like the prairie falcon ( Falco mexicanus ), the Cooper's Hawk ( Accipiter cooperii ), the goshawk ( Accipiter gentilis ), the Red-tailed Hawk ( Buteo jamaicensis ) and the Hudson consecration ( Circus hudsonius ). As parasites several are ticks and fleas known wherein the parasite density compared to other Erdhörnchen low. The populations sometimes live very isolated and are sometimes genetically very different, as there is little or no genetic exchange between the populations.
Systematics
The Idaho ground squirrel is classified as a separate species within the genus Urocitellus , which consists of twelve species. The species has long been classified as part of the ground squirrel and within the subgenus Spermophilus . After a comprehensive molecular biological investigation, however, the species was assigned to the now independent genus Urocitellus together with several other species . The first scientific description comes from the American zoologist Arthur Holmes Howell from 1928, who described it using individuals from New Meadows in Adams County , Idaho, as Citellus townsendi brunneus and thus as a subspecies of the Townsend ground squirrel . Ten years later, in 1938, he raised the Idaho ground squirrel as part of the new description of the Washington ground squirrel ( Citellus washingtoni , today Urocitellus washingtoni ) and named it Citellus brunneus .
Within the species, together with the nominate form, two subspecies are distinguished:
- Urocitellus brunneus brunneus : nominate form, in the northern part of the distribution area from the Seven Devils Mountains to east of the West Mountains in Valley and Adams County , Idaho. The back fur is dark gray with a reddish wash.
- Urocitellus brunneus endemicus : in the southern part of the range in Washington , Payette and Gem Counties , Idaho. The subspecies occurs at lower altitudes than the nominate form, it is grayer and the base of the legs and tail are brown.
Status, threat and protection
The Idaho ground squirrel is classified as endangered by the International Union for Conservation of Nature and Natural Resources (IUCN). This is justified by the very small and highly fragmented distribution area of less than 5000 km 2 , the strong decline and deterioration of usable habitats as well as the small number and strong fluctuation of the existing populations, subpopulations and available sexually mature animals, which are mainly due to persecution decline from humans and other disorders. Regionally, the species is regarded as a pest and is controlled.
With the species there are sometimes rapid declines in populations, for example the decline of a population of more than 270 individuals to only 10 remaining animals was documented between 1987 and 1989, which was attributed to a decline in sexually capable females. The loss of meadows and pastures due to the expansion of forest areas is considered to be the main reasons for the decline in stocks and fragmentation. In addition, there is hunting with poison bait and firearms as well as the spread of non - native grasses ( neophytes ) such as Bromus tectorum and Taeniatherum caput-medusaebei with simultaneous displacement of native grasses and bushes. Grazing by cattle, driving on off-road routes and the associated destruction of burrows and competition with the Columbia ground squirrel ( Urocitellus columbianus ) for suitable deep burrows for wintering also contribute to the decline in animals.
supporting documents
- ↑ a b c d e f g h i j k Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012, ISBN 978-1-4214-0469-1 , pp. 352-353 .
- ↑ a b c d Spermophilus brunneus in the IUCN Red List of Threatened Species 2015.4. Listed by: E. Yensen, NatureServe (G. Hammerson), 2008. Retrieved July 12, 2016.
- ↑ Matthew D. Herron, Todd A. Castoe, Christopher L. Parkinson: Sciurid phylogeny and the paraphyly of holarctic ground squirrels (Spermophilus). Molecular Phylogenetics and Evolution 31, 2004; Pp. 1015-1030. ( Full text ( Memento of the original from April 17, 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this note. , PMID 15120398 )
- ↑ Kristofer M. Helgen, F. Russell Cole, Lauren E. Helgen, Don E. Wilson: Generic Revision in the holarctic ground squirrels genus Spermophilus. Journal of Mammalogy 90 (2), 2009; Pp. 270-305. doi : 10.1644 / 07-MAMM-A-309.1
- ↑ a b Spermophilus (Spermophilus) brunneus In: Don E. Wilson , DeeAnn M. Reeder (Ed.): Mammal Species of the World. A taxonomic and geographic Reference. 2 volumes. 3. Edition. Johns Hopkins University Press, Baltimore MD 2005, ISBN 0-8018-8221-4 .
- ↑ Eric Yensen, Paul W. Sherman: Spermophilus brunneus. Mammalian Species 560, 1997; Pp. 1-5. ( Full text ( Memento of the original from March 4, 2016 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this note. )
literature
- Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012, ISBN 978-1-4214-0469-1 , pp. 352-353 .
- Eric Yensen, Paul W. Sherman: Spermophilus brunneus. Mammalian Species 560, 1997; Pp. 1-5. ( Full text )
Web links
- Spermophilus brunneus inthe IUCN Red List of Endangered Species 2015.4. Listed by: E. Yensen, NatureServe (G. Hammerson), 2008. Retrieved July 12, 2016.