OCTOBER 1989 - City of Boulder

HISPID POCKET MOUSE
Perognathus hispidus
Distribution.-The hispid pocket mouse is a species of the Great
Plains, ranging from southern North Dakota southward to central Mexico
and from the Missouri River to the Rockies. In Colorado, the species
occurs throughout the eastern plains, including eastern Boulder County.
During the course of the present study, the species was captured on
piedmont grassland at the south end of Mesa Trail.
Description.--Large size and spiny, harsh fur distinguish this
from other pocket mice, and external, fur-lined cheek pouches, grooved
incisors, and short ears distinguish it from the deer mouse, the only
large-sized, long-tailed mouse with which it is sympatric, The animals
are buffy above, white below, and have a fairly prominent yellowish
lateral line.
External measurements of two females from Larimer County were:
total length, 200, 220 mm.; tail, 98, 108; hindfoot, 25, 27; ear, 9, 8;
weight, 39.1, 43.0 gr. Greatest length of skull ranges from about 30 to
35 mm., zygomatic breadth is 15 to 18.
Natural History.--Hispid pocket mice inhabit semi-arid grasslands.
They.are less restricted.to areas of sandy soil than some other pocket
a
mice are, and often they are found in areas of gravelly or rocky loam,
typically with vegetation of.bunchgtasses, low shrubs, yucca, and cacti.
The animals are active burrowers. Burrows may have two or three entrances,
which may be marked with small mounds of earth, rather like those of pocket
gophers but smaller. They also may burrow into roadcuts, cutbanks, or
beneath shrubs, as kangaroo rats do. Burrows are plugged during the day.
The animals are nocturnal and active throughout the year. Mostly they
are solitary.
Food consists almost entirely of seeds, including those of grasses,
forbs, and shrubs. Diets in Colorado have not been detailed, but in West
Texas, seeds of sunflower, sagebrush, cacti, Gaillardia, and bluestem
were prominent in the diet, along with cultivated grains (sorghum, millet).
Some insects were eaten, especially'in spring.
Females bear two or more litters of young annually, giving birth to
litters of two to nine young from April or May to September. The young
are altricial, but development has not been studied, and longevity is
unknown.
Owls are known to prey on these pocket mice, and other prairie pre-
dators do as well. No studies of the population ecology of this species
have been done; indeed, its biology generally is poorly known.
Selected References.--Alcoze and Zimmerman (1973); Jones et al.
(in press); Maxell and Brown (1968); Turner (1974).
D.M.A.