Otospermophilus variegatus
Creators: name: Wilson, Don E.
name: Thomas E. Lacher, Jr
name: Mittermeier, Russell A.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Rodentia
Sciuridae
Otospermophilus
Otospermophilus variegatus

description: 219. Common Rock Squirrel <i>Otospermophilus variegatus</i> <b>French:</b> Spermophile des rochers / <b>German:</b> Felsenziesel / <b>Spanish:</b> Ardilla de rocas <b>Taxonomy.</b> Sciurus variegatus Erxleben, 1777, “Mexico.” Restricted by E. W. Nelson in 1898 to Valley of Mexico, near City of Mexico, Distrito Federal, Mexico. Eight subspecies are recognized. <b>Subspecies and Distribution.</b> O.v.variegatusErxleben,1777—CNayarit,SZacatecas,andNSanLuisPotositoMichoacan,Puebla,andNOaxaca(Mexico). O.v.buckley:Slack,1861—CTexastoRioGrande(USA). O.v.couchiiBaird,1855—EChihuahua,Coahuila,andWNuevoLeon,StoNZacatecas,NSanLuisPotosi,andWTamaulipas(Mexico). O.v.grammurusSay,1823—SWUtah,Colorado,SECalifornia,Arizona,NewMexico,andWTexas(USA),extendingStomostofSonoraandCChihuahua(Mexico. O.v.robustusDurrant&amp;Hansen,1954—ECNevada(USA). O.v.rupestrisJ.A.Allen,1903—ESonoraandSChihuahuatoCNayaritandCZacatecas(Mexico). O.v.tularosaeBenson,1932—SCNewMexico(USA). O. v. utah Merriam, 1903 — Utah to S Nevada and NW Arizona (USA). <b>Descriptive notes.</b> Head-body 430-540 mm, tail 174-263 mm; weight 470-875 g (males) and 450-796 g (females). The Common Rock Squirrel has highly variable pelage. Dorsal pelage ranges from grayish mixed with cinnamon buff to light brown to bone brown to dark blackish brown. Sometimes head, shoulders, or nearly entire dorsum can be black. Head fur ranges from pinkish buff to cinnamon-buff to seal-brown to fuscous black. Eyes are encircled by prominent white to buff to tawny rings, and ventral pelage ranges from grayish white to cinnamon-buff. Tail is large and very bushy, similar to tail of tree squirrels, colored with mix of black or brown and buffy white. Nominate variegatus has blackish head, gray dorsum, and grizzled black and white tail. Subspecies buckleyi is small and has dark dorsal pelage. Subspecies couchii is small, with pale pelage dominated by brown, including dark brown cap on head and shoulders. Subspecies grammurus is also small and pale, without dark color on head. Subspecies robustus is larger, with brownish black head, white in upper dorsum, and cinnamon buffin lower dorsum; eye rings are creamy white. Subspecies rupestris is pale, with dorsum dominated by brown or buff, dark brown head, and buff under parts. Subspecies tularosae lacks black in head and dorsum and has tawny posterior dorsum. Subspecies utah is diminutive, with dark dorsum due to an increased infusion of tawny. Chromosomal complement is 2n = 38 and FN = 72. Karyotype consists of eleven pairs of metacentric chromosomes, seven pairs of submetacentric autosomes, metacentric X-chromosome, and acrocentric Y-chromosome. <b>Habitat.</b> Semiarid regions with rocky canyons, cliffs, and hillsides. Common Rock Squirrels are very adaptable and also occur in urban areas, such gardens, parks, and campgrounds. <b>Food and Feeding.</b> Diet of the Common Rock Squirrel consists mostly of buds, flowers, fruits, nuts, cacti, tree seeds (acorns and juniper berries), and cultivated crops (grapes and corn/maize). It also consumes animal matter, such insects, earthworms, and small vertebrates. It is a good climber and often forages in trees. <b>Breeding.</b> Male Common Rock Squirrels emerge from hibernation 2-3 weeks before females, and unlike many other ground squirrel species, they are not yet ready to breed. Females are also not ready to breed when they emerge. Breeding season is long compared with other ground squirrels, lasting up to two months (March—July). Gestation is ¢.30 days. Litters are 3-8 young (average 4-8), are born in, and weight an average of 7-8 g. Young emerge from burrows at c¢.8 weeks old and are weaned after 2—4 more weeks. It is believed that females may have a secondlitter in mild climates, but there is little evidence. Lactating females are found in May—October. Juveniles usually grow slowly, reaching adult weight in their second year. <b>Activity patterns.</b> The Common Rock Squirrel is diurnal and terrestrial and hibernates in burrows for 1-6 months/year. In mild weather regions, it can be active throughout winter. <b>Movements, Home range and Social organization.</b> The Common Rock Squirrel is usually colonial, with several females in a colony, overlapping home ranges, and welldefined dominance system. Overlapping home ranges of females (3-8-4-5 ha) are smaller than those of males (7-9 ha). Although there is high spatial and temporal overlap among individuals, interactions are rare. Scent marking is a significant means of communication. All juvenile males and some females disperse from natal areas. Burrow entrance is nearly always among rocks, boulders, or trees that provide safety, although some individuals have been reported to use arboreal nests. Burrows are up to 6 m long and moderately complex, with few openings and a nest chamber more than 1 m belowground. Within a colony, there is one dominant male and a number of subordinate males. Alarm calls consist primarily of long and short whistles that are difficult to locate. When a snake is spotted, Common Rock Squirrels quickly approach it, kick soil on it, and flag their tails from side to side. Some populations of Common Rock Squirrels are resistant to rattlesnake poison. <b>Status and Conservation.</b> Classified as Least Concern on The IUCN Red List. Current population trend of the Common Rock Squirrel is stable, and there are no major threats. There are several protected areas in its distribution. It is not hunted, but it is shot and poisoned where considered a pest. <b>Bibliography.</b> Botello et al. (2007), Groves et al. (1988), Hayssen et al. (1993), Nelson (1898), Ortega (1987, 1990a, 1990b), Owings et al. (2001), Shriner &amp; Stacey (1991), Thorington et al. (2012).
description: Published as part of <i>Don E. Wilson, Thomas E. Lacher, Jr &amp; Russell A. Mittermeier, 2016, Sciuridae, pp. 648-837 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions</i> on page 807, DOI: 10.5281/zenodo.6840226