Urocitellus brunneus

In this database we are treating Urocitellus brunneus and U. endemicus as separate taxa following Hoisington-Lopez et al. (2012) who determined that elevating subspecies Urocitellus brunneus brunneus and U. b. endemicus to species status is warranted under the cohesion species concept. The American Society of Mammalogists states that although the subspecies endemicus is occasionally considered a distinct species, this has not been followed in most subsequent publications and the data presented in the publication splitting the two species does not appear to strongly support a two species model (ASM 2025).

Molecular phylogenetic studies suggest that the traditionally recognized genera Marmota (marmots), Cynomys (prairie dogs), and Ammospermophilus (antelope ground squirrels) render Spermophilus paraphyletic, potentially suggesting that multiple generic-level lineages should be credited within Spermophilus (Helgen et al. 2009). As a result, ground squirrels formerly allocated to the genus Spermophilus (sensu Thorington and Hoffman, in Wilson and Reeder 2005) are now classified in 8 genera (Notocitellus, Otospermophilus, Callospermophilus, Ictidomys, Poliocitellus, Xerospermophilus, and Urocitellus). Spermophilus sensu stricto is restricted to Eurasia.

Electrophoretic analyses yielded equivocal results regarding the species versus subspecies status of endemicus and brunneus (Gill and Yensen 1992).

Restricted range in west-central Idaho; declined from about 5000+ individuals in 1985 to only 450-500 individuals in 23 sub-populations in 2002. Population has rebounded to around 1500 individuals (Evans and Mack 2010). Populations on the Payette National Forest have appeared to respond positively to management activities aimed at improving habitat suitability and increased acreage of meadow habitat.

Presently is known only from Valley and Adams counties at mid-elevations of 1150-1550 m; most populations are small and often isolated by several kilometers (Yensen 1991). Entire range is 29 by 32 kilometers, or about 928 square kilometers (USFWS 2002).

In 2010 there were 56 known sites, an increase from the 22 occupied sites documented in 2002 (USFWS 2011).

Most threatened by loss and fragmentation of meadow habitat, primarily due to dense regrowth of conifers as a result of fire suppression and ecological succession following logging; but agricultural conversion, road construction, and residential and golf course development also destroy and fragment habitat (Sherman and Yensen 1994, USFWS 2000, USFWS 2002). Other threats include grazing by domestic livestock, off-road vehicle use (may destroy burrows), competition with Columbian ground squirrels (which may exclude S. brunneus from deeper soils that provide more favorable conditions for hibernation), and some recreational shooting (USFWS 2002).