Otospermophilus variegatus

Common Rock Squirrel
(*Otospermophilus variegatus*)
Common Rock Squirrel (Otospermophilus variegatus)
Range
Taxonomic classification
Order:	Rodentia
Suborder:	Sciuromorpha
Family:	Sciuridae
Subfamily:	Xerinae
Tribe:	Marmotini
Genus:	Otospermophilus
Binomial details
	Otospermophilus variegatus (Erxleben, 1777)
Other resources
	Full taxonomic details at MDD

The Common Rock Squirrel (Otospermophilus variegatus) is a bushy-tailed ground squirrel. It occupies semiarid regions with rocky canyons, cliffs, and hillsides (Wilson et al., 2016). It is the largest ground squirrel within its geographic range.

Description

From Oaks et al. (1987): "The head and eyes of the rock squirrel are large, and the ears extend above the top of the head and are much longer than wide. The neck is moderately long for a squirrel but stout, and the limbs are of medium length in comparison with those of other squirrels, with the forelimbs shorter than the hind limbs. The tail is long and bushy, though less so than in typical tree squirrels... pelage with a variegated pattern of black, white, and buff."

Museum images

Holotype: USNM 148289. Otospermophilus variegatus grammurus. Adult male. Glenwood, on the Rio San Francisco at the southwest base of the Mogollon Mountains, Catron County, New Mexico. Collected 2 November 1906. Dorsal view of the skin.
Holotype: USNM 148289. Otospermophilus variegatus grammurus. Adult male. Glenwood, on the Rio San Francisco at the southwest base of the Mogollon Mountains, Catron County, New Mexico. Collected 2 November 1906. Ventral view of the skin.

External measurements

Length measurements are in millimeters (mm) and weight measurements are in grams (g), unless stated otherwise. If available, the sample size (n=) is provided. If a range is not provided and n= is not given, then the listed measurement represents an average.

Part of range	Reference	Total length	Tail length	Hindfoot length	Ear length	Mass
California	Jameson & Peeters (2004)	434–510	198–235	53–60	15–19	580–795
Colorado	Armstrong et al. (2010)	440–530	160–230	53–63	17–27	650–1,000
Texas	Schmidly & Bradley (2016)	468	210	57		600–800

Color variation

This section shows some of the color variation present in Otospermophilus variegatus. The location is provided for reference only. The individual shown does not necessarily represent the only color variant within the local population.

Otospermophilus variegatus observed by Rick Overson and Laura Steger in the Superstition Mountains of Arizona.
Otospermophilus variegatus observed by Chris Bentley near San Antonio, Texas.
Otospermophilus variegatus observed by Chris Bentley near San Antonio, Texas.

Skull

Holotype: USNM 148289. Otospermophilus variegatus grammurus. Adult male. Glenwood, on the Rio San Francisco at the southwest base of the Mogollon Mountains, Catron County, New Mexico. Collected 2 November 1906. Dorsal view of the skull.
Holotype: USNM 148289. Otospermophilus variegatus grammurus. Adult male. Glenwood, on the Rio San Francisco at the southwest base of the Mogollon Mountains, Catron County, New Mexico. Collected 2 November 1906. Ventral view of the skull.
Holotype: USNM 148289. Otospermophilus variegatus grammurus. Adult male. Glenwood, on the Rio San Francisco at the southwest base of the Mogollon Mountains, Catron County, New Mexico. Collected 2 November 1906. Lateral view of the skull.
Holotype: USNM 148289. Otospermophilus variegatus grammurus. Adult male. Glenwood, on the Rio San Francisco at the southwest base of the Mogollon Mountains, Catron County, New Mexico. Collected 2 November 1906. Dorsal view of the mandible.
Holotype: USNM 148289. Otospermophilus variegatus grammurus. Adult male. Glenwood, on the Rio San Francisco at the southwest base of the Mogollon Mountains, Catron County, New Mexico. Collected 2 November 1906. Lateral view of the left mandible.

Similar species

Comparison with Otospermophilus beecheyi

From Smith et al. (2016): "O. beecheyi differs from O. variegatus, the rock squirrel, in that O. variegatus has a dark grayish dorsum mixed with cinnamon buff. The dorsum of O. variegatus may also be light brown to bone brown to dark blackish brown; its head and shoulders are often black. The eye ring of O. variegatus is sometimes white like that of O. beecheyi, but O. variegatus has a buff or tawny dorsum and a grayish white to cinnamon buff venter (Thorington et al. 2012)."

Common Rock Squirrel (Otospermophilus variegatus) observed by Tim Healy at the Grand Canyon in Arizona.
California Ground Squirrel (Otospermophilus beecheyi) photographed by Nathan Petersen near Pasadena, California. © Nathan Petersen

Comparison with Otospermophilus douglasii

From Long and Smith (2023): "The grayish brown fur with speckled white spots on the dorsum of O. douglasii distinguishes it from O. variegatus, the rock squirrel. Specifically, in addition to having grayish brown fur, the dorsum of O. variegatus typically includes a mixture of cinnamon buff and light brown to bone to dark blackish-brown fur (Thorington et al. 2012). In some instances, the entire dorsum of O. variegatus is black, a feature that is absent from O. douglasii (Thorington et al. 2012)."

Common Rock Squirrel (Otospermophilus variegatus) observed by Tim Healy at the Grand Canyon in Arizona.
Douglas's Ground Squirrel (Otospermophilus douglasii) observed by Jonathan Eisen. The charcoal to blackish-brown triangular patch extending from the nape of neck to about midway down the back help to distinguish this species from other ground squirrels.

References

Oaks EC, Young PJ, Kirkland GL, Schmidt DF. 1987. Spermophilus variegatus. Mammalian Species (272):1-8. https://doi-org.ezproxy1.lib.asu.edu/10.2307/3503949

Smith JE, Long DJ, Russell ID, Newcomb KL, Muñoz VD. 2016. Otospermophilus beecheyi (Rodentia: Sciuridae). Mammalian Species 48(939):91-108.

Thorington Jr. RW , Koprowski JL, Steele MA, Whatton JF. 2012. Squirrels of the world. Johns Hopkins University Press, Baltimore, Maryland, USA.

Wilson DE, Lacher Jr TE, Mittermeier RA. 2016. Sciuridae. In: Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I. Barcelona: Lynx Edicions: 648-837, ISBN: 978-84-941892-3-4, DOI: http://doi.org/10.5281/zenodo.6840226