Family: Heteromyidae, Pocket Mice and Kangaroo Rats view all from this family
Description Soft-furred. Pale yellowish above, often with many black hairs; belly white. Yellow patch behind ear; white spot below ear. Small hindfoot. Juvenile dull gray. L 3 7/8-4 3/4" (100-122 mm); T 1 3/4-2 3/8" (44-60 mm); HF 5/8" (16-17 mm); Wt 1/4 oz (6-9 g).
Similar Species Plains Pocket Mouse lacks yellow patch behind ear. Arizona and Little pocket mice are larger, with larger hindfeet. Merriam's Pocket Mouse is very similar, but differs genetically and usually has a somewhat longer tail.
Breeding In New Mexico, breeding activity peaks April-July and September-October. Usually ceases in winter, but some may breed in January and produce young in February. 1 or 2 litters per year of 1-6 (average 3 or 4) young, born after gestation of 22-26 days.
Habitat Prairies; sandy, gravelly, or rocky areas with sparse vegetation of various grasses and forbs.
Range Southeastern Wyoming and w Nebraska south to extreme se Utah, Arizona, New Mexico, and w Texas.
Discussion The Silky Pocket Mouse is nocturnal. It sometimes hibernates; otherwise it may forage nightly throughout winter, although its activity may be reduced. The animal enters its small burrow through a mound of dirt. The burrow is usually not more than 4 inches (100 mm) deep, and often has several entrances from different levels on the mound. Inside the mound there is a central chamber from which a single tunnel goes down into a second chamber, larger than the first. The nest is about 2 1/2 inches (65 mm) in diameter, with one opening near the top of the mound. Tunnels radiate from the nest chamber and often contain small caches of seeds. Additional seeds are stored regardless of the number of caches already existing. Burrows often are found under cactus, yucca, or shrubs. Burrows in a plowed field in Zacatecas, Mexico, were 2 to 4 inches (50-100 mm) deep, and extended up to about 3 feet (1 m) long. Blind passages near the surface enable the Silky Pocket Mouse to break through to escape snakes and other underground predators. This species sometimes uses abandoned burrows of other pocket mice, kangaroo rats, or pocket gophers. It has been known to inhabit the mounds of harvester ants, presumably to obtain seeds gathered by the ants. Like many other pocket mice, it drinks no water, metabolizing it from food. The latter is primarily seeds, but this pocket mouse also eats other plant material--including the small seeds of thistle and millet, as well as several grasses, wild sunflowers, amaranth pigweed, and opuntia--along with very few invertebrates. Predators include gopher snakes, coachwhips, rattlesnakes, owls, foxes, Coyotes, skunks, American Badgers, and Ringtails.
