By Kevin Schiebenes
Geographic Range
The range of Bailey's pocket mice (Chatodipus baileyi) is coincidental with the Sonoran Desert. They inhabit the entire length of the Baja California Peninsula, along with some small coastal islands. The species ranges from far southwestern New Mexico, along the southern part of Arizona, to the extreme southern part of California. In Mexico, the species is found from the western half of Sonora to northern Sinaloa. (Paulson, 1988)
Habitat
(885.6 to 2361.6 ft)
Bailey's pocket mice occur primarily in the lower Sonoran Desert transition zone, often between rocky hillsides and desert flats. They use areas under large bushes and trees. (Brylski, 1999; Paulson, 1988)
These animals are found in the following types of habitat:
terrestrial 
.
Terrestrial Biomes:
desert or dune .
Physical Description
(0.84 to 1.34 oz)
(6.93 to 9.45 in)
Bailey's pocket mice range in mass from 24 to 38 g. Males are slightly heavier than females, weighing in at an average of 28.2 g, compared to the average of 24.5 g for females. The total length of thse animals ranges between 176 and 240 mm, of which the tail contributes an additional 112 to 127 mm to the total length. They are considered the largest of the soft-haired pocket mice with crested tails. The pelage is grayish above, with varying degrees of yellow "washed in". The under parts are whitish. The dental formula is i 1/1 c 0/0 p 1/1 m 3/3 20. (Burt and Grossenheider, 1980; Paulson, 1988)
Some key physical features:
endothermic ; bilateral symmetry .
Sexual dimorphism: male larger.
Reproduction
The breeding interval has not been reported for this species.
Chatodipus baileyi breeds in spring and summer months.
No information was found about the mating systems of Bailey's pocket mice. However, their sexual dimorphism in size indicates that the species may be polygynous, with males competing for access to females.
The breeding activity of Bailey's pocket mice is confined to the spring and summer months, with highest breeding activity in the late spring. This high point of sexual activity is correlated with new vegetative growth within their range. The young are usually born in April and May. The general litter size is 3 to 4 pups. Young of the year are thought to be able to reproduce before the end of the breeding season. (Burt and Grossenheider, 1980; Paulson, 1988; Reynolds and Haskell, 1949)
Although details are lacking for this species, other members of the genus are known to have gestation periods around 23 days. Young are altricial at birth, but develop quickly. Eyes are open by 18 days of age, and young are able to eat seeds by 24 days of age. Weaning probably occurs around this time. It is likely that C. baileyi is similar to other members of the genus in these areas. (Nowak, 1999)
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous .
Information on parental care in this species is not available in the literature. However, as mammals, we know that the mother provides the growing young with milk, grooming, and protection. Because members of this genus are altricial at birth, the mother probably constructs some type of nest, in which she keeps the young until they are able to venture forth on their own. In other members of the genus, young are able to consume seeds around the age of 24 days. It is likely that C. baileyi is similar, and that the young become independent of the mother shortly after this age. Male parental care has not been reported for these animals. (Nowak, 1999)
Parental investment:
no parental involvement; altricial ; pre-fertilization (protecting: female); pre-hatching/birth (provisioning: female, protecting: female); pre-weaning/fledging (provisioning: female, protecting: female).
Lifespan/Longevity
Bailey's pocket mice have a relatively long life span, and can live up to 3 years in captivity. (Paulson, 1988)
Behavior
Individuals are active all year round with peak activity in autumn. Activity is reduced during December. (Paulson, 1988)
Other details on behavior of this species are scant. Chatodipus baileyi are known to use areas with shubs that serve as vegetative cover. The species is nocturnal, and these bushes probably help to protect them from predators. Other members of the genus construct burrows, and C. baileyi is probably similar in this respect. (Nowak, 1999)
Home Range
The home range of Bailey's pocket mice can vary from 0.12 to 0.24 ha. (Brylski, 1999)
Key behaviors:
terricolous; nocturnal ; motile ; solitary ; territorial .
Communication and Perception
No information was found about communication for Bailey's pocket mice. However, it is likely that they use some visual signals, vocalizations, and tactile communication. As mammals, it is likely that they also have some forms of chemical communication, as scent is often used for individual identification, as well as marking territories, and helping to identify reproductive condition of conspecifics.
Food Habits
Bailey's pocket mice are dietary generalists. They utilize a variety of seeds and varying amounts of insects and green vegetation. The daily nutritional requirements can theoretically be met through a single feeding episode by loading their large cheek pouches. Although not specifically reported for this species, other members are known to cache seeds. It is likely that this species does so as well, as it is able to carry seeds in its cheek pouches. (Nowak, 1999; Paulson, 1988)
Animal Foods:
insects.
Plant Foods:
leaves; seeds, grains, and nuts.
Foraging Behaviors:
stores or caches food .
Predation
- coyotes (Canis latrans)
- American badgers (Taxidea taxus)
- owls (Strigiformes)
- snakes (Serpentes)
Bailey's pocket mice are preyed upon by owls, coyotes, badgers, and snakes. (Brylski, 1999)
Ecosystem Roles
Bailey's pocket mice are nocturnal granivores and are prey for snakes, owls, coyotes, and badgers. They compete with ants and other desert-dwelling rodents for food. It is thought that this species may select larger seeds than other similar sized rodents, helping to partition the seed-eating niche. Through their seed caching, these rodents help to distribute seeds. Through their burrowing, they help to aerate the soil. (Brylski, 1999; Paulson, 1988)
Key ways these animals impact their ecosystem:
disperses seeds; soil aeration .
Economic Importance for Humans: Negative
No information was found for negative economic impacts on humans.
Economic Importance for Humans: Positive
It is unlikely that these small, seed eating rodents have any direct economic impact on humans. However, they do serve as food for larger species which humans enjoy watching, so there is some indirect connection.
Conservation Status
IUCN Red List: [link]:
Lower Risk - Least Concern.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
Baily's pocket mice are not listed by CITES or IUCN. (IUCN, 2002; NatureServe, 2001; UNEP-WCMC, 2002)
Contributors
Nancy Shefferly (editor), Animal Diversity Web Staff.
Kevin Schiebenes (author), University of Wisconsin-Stevens Point. Chris Yahnke (editor, instructor), University of Wisconsin Stevens Point.
