Urocitellus brunneus (A. H. Howell, 1928)
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publication ID |
https://doi.org/ 10.5281/zenodo.6840226 |
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DOI |
https://doi.org/10.5281/zenodo.6840664 |
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persistent identifier |
https://treatment.plazi.org/id/064D0660-FF92-ED6F-FFC9-F753F6DEF290 |
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treatment provided by |
Diego |
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scientific name |
Urocitellus brunneus |
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210. View On
Idaho Ground Squirrel
Urocitellus brunneus View in CoL
French: Spermophile d'ldaho / German: Idaho-Ziesel / Spanish: Ardilla terrestre de Idaho
Taxonomy. Citellus townsendii brunneus A. H. Howell, 1928 ,
“New Meadows, Ad-
ams County, Idaho, [USA].”
Two highly genetically distinct subspecies might be two separate species. Two subspecies recognized.
Subspecies and Distribution.
U.b.brunneusA.H.Howell,1928—Npartofthedistribution,inValleyandAdamscounties,Idaho(USA).
U. b. endemicus Yensen, 1991 — S part of the
distribution in Washington, Payette, and Gem counties in Idaho (USA).
Descriptive notes. Head-body mean 183-4 mm (males) and 173-6 mm (females), tail 55-1 mm (males) and 54-7 mm (females); weight mean 118-9 g (males) and 116-8 g (females). The Idaho Ground Squirrel is small and recognized by its small head and body, short tail, distinct eye ring, and brownish dorsal pelage, with white spots. Nose, legs, and ventral surface oftail are yellow-pink to orange. Nominate brunneus is the more reddish, and dark subspecies and found at higher elevation.
Habitat. Open meadows of mixed forbs and grasses. The Idaho Ground Squirrel extends into open park-like forests but quickly disappears from open conifer stands when fire suppression and timber harvest increases canopy cover and woody encroachment that result in tall dense exotic or barren herbaceous understory. Subspecies endemicus occurs at lower elevations than brunneus (less than 1000 m). Low burrow densities are associated with exotic and annual plant cover; high burrow densities are associated with native and perennial plant cover.
Food and Feeding. The Idaho Ground Squirrel is a generalist herbivore, feeding primarily on grasses, forbs, leaves, flowers, roots, bulbs, and some seeds later in the season. Is known to seek and eat fungi and will consume insects and scavenge animal tissue.
Breeding. Idaho Ground Squirrels inhabits burrows with a vegetation-lined nest chamber in which young are born, but they also use shallow escape burrows or more substantial hibernacula. Males emerge c.2 weeks before females and court, guard, and copulate within 1-2 days of female emergence. Mating usually occurs belowground. Guarding of females continues if density of receptive females is low; otherwise, males might seek other females over a breeding season that lasts 12-13 days. Duration and order of mating are important; last male to guard the female fathers more than 65% of young. Copulatory plugs are produced perhapsto preserve this last male-mating advantage. Large males dominate small males. Single litters averaging 5-2 young emerge from late March to early April in subspecies endemicus or 5-6 weeks later in brunneus.
Activity patterns. Idaho Ground Squirrels are diurnal. They are active aboveground from late January to early August, usually less than c.4 months for an individual. Males emerge slightly earlier than females and enter hibernacula a bit earlier in summer.
Movements, Home range and Social organization. Distribution of the Idaho Ground Squirrel is fragmented, with northern subpopulations of brunneus at very low densities. In the late 1980s, populations of brunneus declined dramatically to ten animals in one isolated population. Range-wide population declined from 40,000 individuals in 1984 to 4000 in 2000, with local extirpation of some populations. Individuals live in low-density colonies but appear to be relatively solitary within local aggregations. One simple shrill alarm call is used when threatened.
Status and Conservation. Classified as Endangered on The IUCN Red List. Population of the Idaho Ground Squirrel is considered to have declined due to fire suppression, timber harvest, and invasions by non-native annual grasses that decrease meadow quality; habitat restoration and translocations have resulted in population increases in recent years. Subspecies brunneus is considered highly threatened, and in 2000, it was formally listed as threatened under the US Endangered Species Act.
Bibliography. Gavin et al. (1999), Hoisington-Lopez et al. (2012), Lohr et al. (2013), Mateju & Kratochvil (2013), Sherman (1989), Sherman & Runge (2002), Suronen & Newingham (2013a, 2013b), Thorington et al. (2012), Yensen (1991), Yensen & NatureServe (Hammerson etal.) (2008), Yensen & Sherman (1997).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
