Montana Field Guide

The pelage of the Hispid Pocket Mouse is harsh, with a rump patch of noticeable spiny bristles. It is ochraceous-buff above and mixed with blackish hairs, the belly is white, and separated from the back by a distinctive lateral stripe of buffy hairs. The tail is sharply bicolored, dark to blackish above and white below, and is equal to or shorter than the length of the head and body. It has fur-lined cheek pouches, as in other pocket mice, but the hind feet are naked. Adults from Nebraska attain the following body measurements: total length 203 to 237 millimeters; tail length 93 to 114 millimeters; hind foot length 23.5 to 29.5 millimeters; and mean weight 32.0 grams (Paulson 1988).

Respective measurements for the lone specimen from Montana are total length 191 millimeters, tail length 94 millimeters, hind foot length 28 millimeters, and weight 33.2 grams (Pefaur and Hoffmann 1971).

The Hispid Pocket Mouse is the largest pocket mouse in Montana and is distinguished by its rough dorsal pelage and the naked soles of its hind feet. On the skull, the mastoids do not project beyond the occipital plane and the auditory bullae are clearly separated. The combination of grooved incisors, hypsodont molars, perforate nasal septum, and fur-lined external cheek pouches distinguish the hispid pocket mouse from other non-heteromyid rodents. For other heteromyid species in Montana, Ord's Kangaroo Rat (Dipodomys ordii) also differs by having greatly elongated hind legs, hind foot length more than 30 millimeters, and the mastoid (rear) region of the skull greatly expanded. The Olive-backed Pocket Mouse (Perognathus fasciatus) also has an unlobed antitragus (fleshy projection) in the ear, occipitonasal length (anterior tip of nasal bone to posterior tip of occipital bone at base of skull) less than 24 millimeters, a uniformly-colored tail, and a hind foot length less than 20 millimeters. The range of the smaller Great Basin Pocket Mouse does not overlap in Montana with the Hispid Pocket Mouse (Foresman 2012a, 2001b).

The Hispid Pocket Mouse is non-migratory; no information on dispersal is available.

The only Montana record for Hispid Pocket Mouse occurred on a north-facing slope that supported grassland dominated by Stipa comata, Carex filifolia, Andropogon scoparium, Agropyron smithii, Aristada longiseta, and Bouteloua gracilis (Pefaur and Hoffmann 1971). Information from other parts of its range suggests that the Hispid Pocket Mouse prefers prairie areas with sparse or moderate vegetation, and has been found in a variety of dry grassland and shrub-grassland habitats. It also occurs in rocky or gravelly areas with heavy soils, not being restricted to sandy soils as are other prairie pocket mice. It has also been found in irrigated cornfields and hayfields. Sleeping and birthing occur in underground burrows (Paulson 1988, Seabloom 2002).

The Hispid Pocket Mouse eats mostly seeds of grasses, forbs, shrubs, and cacti in winter (81% of the diet in parts of Texas), but also consumes green leaves and some insects (mostly ground beetles) in spring. Large quantities of seeds are stored underground for winter use (Jones et al. 1983, Paulson 1988). The diet in Montana is unknown.

Hispid Pocket Mice are generally solitary and nocturnal. Unlike some other pocket mice, Hispid Pocket Mice are active all year. They leave mounds of dirt at the multiple entrances to their burrows, and entrances are often plugged during the day. Burrows are often dug at the base of shrubs or rock outcrops, and seeds are stored in shallow underground chambers. Predators include rattlesnakes, and most nocturnal carnivorous mammals and birds; Great Horned Owls in Nebraska and Oklahoma prey on this species (Jones et al. 1983, Clark and Stromberg 1987, Paulson 1988). In Montana, other small mammals found in sympatry with Hispid Pocket Mouse included Prairie Vole, Olive-backed Pocket Mouse, Meadow Jumping Mouse, Deer Mouse, and Western Harvest Mouse (Pefaur and Hoffmann 1971).

Populations never seem to be especially dense, thus estimates of density, home range size, and dispersal are not available.

No information specific to Montana is documented. The single individual captured in Montana (in mid-July) was a nulliparous subadult female (Pefaur and Hoffmann 1971).

Throughout its range very little is known about the reproductive biology of this species. It breeds in spring and summer in the north, probably throughout the year in the south, and likely produces 1 to 2 litters of 2 to 9 young; August and September females from South Dakota and Nebraska carried 5 to 6 fetuses (Jones et al. 1983, Paulson 1988).

No special management activities have been developed or implemented for this species in Montana. A thorough small mammal survey of appropriate grassland and shrub-grassland habitats in southeastern Montana is desirable to define the distribution and relative abundance of this species in the state.