Perception Channels: tactile ; chemical
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
No literature available to identify negative economic importance to humans.
No literature available to identify positive economic importance to humans.
Rock pocket mice are granivorous, feeding on a variety of seeds depending on availability (Rebar, 1995; Wilson and Ruff, 1999). They are capable of collecting seeds in fur-lined cheek pouches. Cheek pouch volume is directly proportional to body size (Vander-Wall et al., 1998).
Rock pocket mice occur in rocky habitats in the southwestern United States, from south-central Utah through much of Arizona, New Mexico, Texas (western Sonora, Chihuahua and Trans-Pecos), as well as northwestern Mexico (Wilson and Ruff, 1999; Weckerly et. al., 1985; Weckerly et. al., 1988).
Biogeographic Regions: nearctic (Native )
Rock pocket mice inhabit desert and are particularly associated with rocky areas. (Wilson and Ruff, 1999). Average home range size is 400 meters (Krebs et al., 1990).
Terrestrial Biomes: desert or dune
Rock pocket mice range from 157 to 188mm in total length, with a tail length from 84 to 112mm. They weigh between 10.5g. and 19.9g. The tails are long and tufted at the tip (Wilson and Ruff, 1999). Their relative size is small in contrast to other members in their genus (Vaughn, 2000). Body size varies regionally (Weckerly et. al., 1988) Pelage is grayish brown on the back with pale orange brown lines on the sides and white underneath. Hairs are coarse with weak "spines" on the rump (Wilson and Ruff, 1999). The bottoms of their hind feet are bare to the heels (Wilson and Ruff, 1999). Dental formula is 1/1 0/0 1/1 3/3=20 and cheek teeth of are ever growing (Vaughn, 2000). Sexual dimorphism is observed, with males being larger overall and in certain morphological features such as mastoid width, nasal length, and mandible length (Wilson and Ruff, 1999; Weckerly et al., 1988).
Range mass: 10.5 to 19.9 g.
Other Physical Features: endothermic ; bilateral symmetry
The breeding season begins in February or March and progresses into July. Litter size varies from three to six (Wilson and Ruff, 1999). Similar to other species of pocket mice, rock pocket mice live for a maximum of three years (Paulson, 1988). Van de Graff (1975) observed that males tend to be in reproductive condition for longer periods each year than females. In southeastern Arizona all males captured from February until September were fertile. Females are reproductively active from February until the end of July. Males in reproductive condition averaged 2.3g. heavier than those that were not (Van de Graff, 1975). During prolonged droughts reproduction is often delayed and survivorship of young is 7.3% (Paulson, 1988).
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
The rock pocket mouse (Chaetodipus intermedius) is one of 19 species of pocket mice in the genus Chaetodipus. It is sometimes grouped in the genus Perognathus.[2]
Found mainly in rocky outcrops in the deserts of the southwestern United States and Mexico, the rock pocket mouse is medium-sized (length ~18 cm, weight ~12–18g) and nocturnal. It eats mainly plant seeds and makes small burrows in soil close to or under rocks to evade owls, its main predator. The breeding season spans a few months, starting in February or March, and the litter size is typically between three and six. As with most pocket mice, the tail is longer than the body (~10 cm).
Historically, rock pocket mice have been subdivided into as many as ten subspecies (Benson 1933; Dice and Blossom 1937) based on geographical distribution and coat colour. Most rock pocket mouse populations have light, tawny fur consistent with the colour of the desert rocks on which they live. However, darker coloured rock pocket mice are found living amid black, basaltic rock formations.
In 2003, scientists sampled DNA from both light- and dark-coloured rock pocket mice from areas in Pinacate Peaks, Mexico and New Mexico, USA. In the Pinacate mice, they discovered a perfect association between different versions of the Melanocortin-1 receptor (Mc41r6) gene and coat colour .[3] Subsequent studies demonstrated that there is strong selective pressure maintaining Mc1r allele and coat colour frequencies across the short geographic distances between the light- and dark-coloured rock islands.[4]
Thus melanism in rock pocket mice is considered a fabulous example of adaptation by natural selection. Changes in the Mc1r gene sequence are not responsible for the colour difference in the mice sampled from New Mexico, however, leading the researchers to conclude that the almost identical dark coat colours developed multiple times in rock pocket mice, an example of convergent evolution.[5]
The rock pocket mouse (Chaetodipus intermedius) is one of 19 species of pocket mice in the genus Chaetodipus. It is sometimes grouped in the genus Perognathus.
