Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels, and flying squirrels. Squirrels are indigenous to the Americas, Eurasia, and Africa, and were introduced by humans to Australia. The earliest known fossilized squirrels date from the Eocene epoch, and among other living rodent families, the squirrels are most closely related to the mountain beaver and to the dormice.
The western gray squirrel is a tree squirrel found along the western coast of the United States and Mexico. In some places, this species has also been known as the silver-gray squirrel, the California gray squirrel, the Oregon gray squirrel, the Columbian gray squirrel and the banner-tail. There are three geographical subspecies: Sciurus griseus griseus ; S. g. nigripes ; and S. g. anthonyi.
Antelope squirrels or antelope ground squirrels of the genus Ammospermophilus are sciurids found in the desert and dry scrub areas of south-western United States and northern Mexico. They are a type of ground squirrel and are able to resist hyperthermia and can survive body temperatures over 40 °C (104 °F).
The San Joaquin antelope squirrel or Nelson's antelope squirrel, is a species of antelope squirrel, in the San Joaquin Valley of the U.S. state of California.
The American red squirrel is one of three species of tree squirrels currently classified in the genus Tamiasciurus, known as the pine squirrels. The American red squirrel is variously known as the pine squirrel, North American red squirrel and chickaree. It is also referred to as Hudson's Bay squirrel, as in John James Audubon's work The Viviparous Quadrupeds of North America. The squirrel is a small, 200–250 g (7.1–8.8 oz), diurnal mammal that defends a year-round exclusive territory. It feeds primarily on the seeds of conifer cones, and is widely distributed across North America wherever conifers are common, except on the Pacific coast of the United States, where its cousin, the Douglas squirrel, is found instead.
Abert's squirrel or the tassel-eared squirrel is a tree squirrel in the genus Sciurus native to the southern Rocky Mountains from the United States to the northern Sierra Madre Occidental of Mexico, with concentrations found in Arizona, New Mexico, and southwestern Colorado. It is closely associated with, and largely confined to, mature ponderosa pine forests. It is named in honor of the American naturalist John James Abert; nine subspecies are recognised. It is recognizable by its tufted ears, gray color, pale underparts and rufous patch on the lower back. The squirrel feeds on the seeds and cones of the Mexican pinyon and the ponderosa pine when they are available, but will also take fungi, buds, bark, and carrion. Breeding normally occurs in summer, with a spherical nest being built high in the canopy.
Botta's pocket gopher is a pocket gopher native to western North America. It is also known in some sources as valley pocket gopher, particularly in California. Both the specific and common names of this species honor Paul-Émile Botta, a naturalist and archaeologist who collected mammals in California in 1827 and 1828.
The hispid cotton rat is a rodent species long thought to occur in parts of South America, Central America, and southern North America. However, recent taxonomic revisions, based on mitochondrial DNA sequence data, have split this widely distributed species into three separate species. The distribution of S. hispidus ranges from Arizona in the west to Virginia to the east and from the Platte River in Nebraska in the north to, likely, the Rio Grande in the south, where it meets the northern edge of the distribution of S. toltecus. Adult size is total length 202–340 mm (8.0–13.4 in); tail 87–122 mm (3.4–4.8 in), frequently broken or stubbed; hind foot 29–35 mm (1.1–1.4 in); ear 16–20 mm (0.63–0.79 in); mass 50–250 g (1.8–8.8 oz). They have been used as laboratory animals.
The white-tailed prairie dog is found in western Wyoming and western Colorado with small areas in eastern Utah and southern Montana. The largest populations are in Wyoming where they are known colloquially as "chiselers". This prairie dog species lives at an elevation between 5,000 and 10,000 feet, generally a higher elevation than other prairie dog species. Its predators include black-footed ferrets, badgers, and golden eagles.
Ord's kangaroo rat is a kangaroo rat native to western North America, specifically the Great Plains and the Great Basin, with its range extending from extreme southern Canada to central Mexico.
Harris's antelope squirrel is a species of rodent in the family Sciuridae. It is found in Arizona and New Mexico in the United States, and in Sonora in Mexico. They are adapted to hot weather conditions including a technique called "heat dumping". They have a wide-ranging diet, including both vegetation, insects, small rodents and carrion.
The Espíritu Santo antelope squirrel is a species of antelope squirrel in the family Sciuridae. It is endemic to Mexico, where it is known only from the island of Espíritu Santo in the Gulf of California. The species was originally described by Edward William Nelson and Edward Alphonso Goldman in 1909 as a subspecies of the white-tailed antelope squirrel, a wide-ranging species in the southwestern U.S. and Mexico. In 1938, Arthur H. Howell elevated the subspecies to full species status, on the basis of slightly larger skull proportions and the absence or reduction of the third upper premolar. Studies of DNA and chromosomes have variously suggested close relationships with Harris's antelope squirrels or other subspecies of white-tailed antelope squirrel. A 2007 comparison of DNA and morphological traits suggested the differences between Espíritu Santo squirrels and those on the Baja California peninsula and other islands were not enough to warrant distinct species but rather a subspecies of white-tailed antelope squirrels. Since 2008 the IUCN has similarly recognized the Espíritu Santo antelope squirrel as a subspecies of white-tailed antelope squirrel.
The Texas antelope squirrel is a species of rodent in the family Sciuridae. It is found in Mexico and in both Texas and New Mexico within the United States.
The Great Basin pocket mouse is a species of rodent in the family Heteromyidae. It is found in British Columbia in Canada and the western United States.
The Columbian ground squirrel is a species of rodent common in certain regions of Canada and the northwestern United States. It is the second largest member of the genus Urocitellus, which is part of the tribe Marmotini, along with marmots, chipmunks, prairie dogs, and other holarctic ground squirrels. They are stout, with short dense fur, which is characteristically tawny across the bridge of the nose. Social encounters sometimes are initiated with kissing behavior and the most common activity above ground is standing at attention. Residing in mountainous terrain and high plains in northern latitudes, they hibernate for 8 to 9 months of the year in burrows, which may be used for many years. They are emaciated when emerging in the spring. The Columbian ground squirrel came to the attention of the scientific community through writings produced by Lewis and Clark, while 21st century molecular genetics has more finely illuminated its ties with other close relatives.
The Cascade golden-mantled ground squirrel is a species of rodent in the family Sciuridae, in the order Rodentia. It is the largest species of the three within the genus Callospermophilus. It is found in the Cascade Mountains in the province of British Columbia, Canada and the state of Washington, United States.
Townsend's ground squirrel is a species of rodent in the family Sciuridae. It is found in high desert shrublands in several areas of the United States.
The Daurian pika is a small relative of rabbits and hares in the order Lagomorpha. It is well known for its “barking” alarm call, and for its peculiar habit of making hay to help survive the winter. There are 4 recognized subspecies, Ochotona dauurica annectens, O.d. bedfordi, O.d. dauurica, and O.d. mursavi. Daurian pikas, like other lagomorphs, are characterized by a secondary set of incisor teeth. They are sexually monomorphic, with thick reddish coats. Pikas have no external tail, and their ears are large and rounded. The auditory bullae, a feature of the skull of daurian pikas are small in comparison to many other pikas. This is thought to be related to their fairly low altitude habitat preference. They are considered keystone species within their habitat.
The black-tailed jackrabbit, also known as the American desert hare, is a common hare of the western United States and Mexico, where it is found at elevations from sea level up to 10,000 ft (3,000 m). Reaching a length around 2 ft (61 cm), and a weight from 3 to 6 lb, the black-tailed jackrabbit is one of the largest North American hares. Black-tailed jackrabbits occupy mixed shrub-grassland terrains. Their breeding depends on the location; it typically peaks in spring, but may continue all year round in warm climates. Young are born fully furred with eyes open; they are well camouflaged and are mobile within minutes of birth, thus females do not protect or even stay with the young except during nursing. The average litter size is around four, but may be as low as two and as high as seven in warm regions.
