Rock squirrel

This article is about the North American squirrel. For Asian rock squirrels, see Sciurotamias.

The rock squirrel (Otospermophilus variegatus) is a species of rodent in the family Sciuridae. It is native to Mexico and the Southwestern United States, including southern Nevada, Utah, Colorado, Arizona, New Mexico, West Texas, and the panhandle of Oklahoma.

Rock squirrel
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Rodentia
Family:	Sciuridae
Genus:	Otospermophilus
Species:	O. variegatus
Binomial name
Otospermophilus variegatus (Erxleben, 1777)
Synonyms
Spermophilus variegatus

Characteristics

Rock squirrels are one of the largest members of the family Sciuridae, with adults measuring up to 21 inches (53 cm) in length. In front and on top, the squirrel's coat is a speckled grayish brown; on the rear and bottom, the gray becomes a more mottled brownish-black tone. They have a marked light-colored ring around their eyes and pointed ears that project well above their heads. Rock squirrels have a long, bushy tail with white edges.

• Alarm call
• 
  at Water Ranch Lake, AZ

Life history/behavior

The female rock squirrel has two litters a year, with three to nine young in each litter. The first litter is typically born from April to June, while the second is born in August or September. They are active in the early morning and late afternoons when the weather is warm; when very hot, they may estivate. They are social, and live in colonies with several females and one dominant male that fights other mature males to protect the group. Subordinate males lurk at the outer boundaries of the group. Rock squirrels dig burrows with their sharp claws and muscular legs. The burrows provide shelter, safety, living space, and food storage. Burrow systems can be complex and lengthy, as they are enlarged over a period of years. Entrances are usually hidden beneath rocks and can be wider than 3 inches. In the northern reach of their habitat, rock squirrels hibernate during the colder months of the year. In southern areas, rock squirrels may not hibernate at all. They can withstand long periods of time without water, some even up to 100 days. When alarmed, they whistle a short, sharp, oscillating call.

Diet

The rock squirrel is predominantly a herbivore, eating mostly leaves, stems, and seeds, and occasionally invertebrates and small vertebrates. They also eat acorns, pine nuts, fruits of native plants, assorted grasses, mesquite, juniper berries, agaves and cacti. The primary invertebrates include grasshoppers, beetles and earthworms and the vertebrates include young wild turkeys and other fowl. The rock squirrel may eat their own kind, scavenging the remains of squirrels that are already dead. Its diet changes with the seasons, accustoming itself to what is available locally.

Rock squirrels forage for their food on a daily basis, by climbing trees and bushes or on the ground. They collect generous amounts of food items in their cheek pouches, which are quite large. One researcher counted 62 Gambel's oak acorns carried in one squirrel's pouch. These foraging trips are generally short-lived, usually only lasting about 12 minutes. Most foraging is done in the morning, to avoid the hotter parts of the day. They eat some of the food right away and bring a significant portion back to a lookout point or burrow, where they can safely consume or store the rest.

Predators

A variety of snakes, birds of prey, and other mammals (bobcats, ringtails, gray foxes, raccoons, coyotes, badgers, domestic cats and dogs) prey upon the rock squirrel. Humans have also been known to eat rock squirrels, but can also view them as pests, resulting in lethal and nonlethal removal. The rock squirrel displays a variety of antipredator behaviors. When close to a snake, they make menacing movements and even throw debris at the snake. They often feed, rest, and sunbathe in trees, high rocks, and stumps. This allows them to watch for predators and to communicate alarm calls to other squirrels. They also emit musky scent from their anal glands when disturbed by predators.

A Rock Squirrel in its natural environment along the Verde River in Arizona.

Geographic Range

Because of their specialized habitat requirements, there's very select states in the US where these creatures can sustain themselves. These squirrels inhabit rocky mountains, canyon walls, cliffs, and steep rocky hills and there's only a few areas within North America with such type of landscape. These squirrels can be found throughout the southern US border along with Mexico in states like California, Arizona, Utah, Colorado, Oklahoma, New Mexico and parts of West Texas. Contrary to popular belief, in Mexico these squirrels are not found in eastern coastal lowlands, but they inhabit areas of Jalisco, Guerrero, Mexico, Morelos, Colima and Puebla. In the western edge of the range of these squirrels in the US, they mostly inhabit parts of southeasternmost corners of California, which includes some of the most arid areas in the entire state.

Sources

• Oaks, Emily C.; Kirkland, Gordon L.; Schmidt, David F.; Young, Paul J. (27 February 1987). "Spermophilus Variegatus (Erxleben, 1777): Rock Squirrel". Mammalian Species (272). The American Society of Mammalogists. doi:10.2307/3503949. JSTOR 3503949.
• Marsh, Rex E. (1994). "Belding's, California, and Rock Ground Squirrels". In Hygnstrom, Scott E.; Timm, Robert M.; Larson, Gary E. (eds.). Prevention and Control of Wildlife Damage. University of Nebraska-Lincoln.

Further reading

• "Rock Squirrel - Spermophilus Variegatus." Rock Squirrel. N.p., n.d. Web. 14 May 2015. (https://nhpbs.org/natureworks/rocksquirrel.htm)
• Walsberg, G., B. Wolf. 1995. Solar heat gain in a desert rodent: unexpected increases with wind speed and implications for estimating the heat balance of free-living animals. Journal of Comparative Physiology, 165 (4): 306-314.
• Schalau, Jeff. "Backyard Gardener - Rock Squirrels - May 27, 2020". cals.arizona.edu. Retrieved 2021-11-30.
• "Rock Squirrel." S. N.p., n.d. Web. 14 May 2015. animals in the United States and Mexico June 26, 2015

External links

• Media related to Otospermophilus variegatus at Wikimedia Commons
• Smithsonian rock squirrel article
• The American Society of Mammalogists species account
• Arizona-Sonora Desert Museum