Chaetodipus baileyiBailey's pocket mouse

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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

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)

  • Range elevation
    270 to 720 m
    885.83 to 2362.20 ft

Physical Description

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)

  • Sexual Dimorphism
  • male larger
  • Range mass
    24 to 38 g
    0.85 to 1.34 oz
  • Range length
    176 to 240 mm
    6.93 to 9.45 in

Reproduction

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)

  • Breeding interval
    The breeding interval has not been reported for this species.
  • Breeding season
    Chatodipus baileyi breeds in spring and summer months.
  • Range number of offspring
    3 to 4

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)

  • Range lifespan
    Status: captivity
    3 (high) years

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)

  • Range territory size
    1200 to 2400 m^2

Home Range

The home range of Bailey's pocket mice can vary from 0.12 to 0.24 ha. (Brylski, 1999)

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

Predation

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)

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.

Economic Importance for Humans: Negative

No information was found for negative economic impacts on humans.

Conservation Status

Baily's pocket mice are not listed by CITES or IUCN. ("Chaetodipus baileyi", 2001; "UNEP-WCMC Species Database: Cites-Listed Species", 2002; "2002 IUCN Red List of Threatened Species", 2002)

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Kevin Schiebenes (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

IUCN. 2002. "2002 IUCN Red List of Threatened Species" (On-line ). Accessed 11/25/02 at http://www.redlist.org/search/search.php?freetext=chaetodipus+baileyi&modifier=phrase&criteria=wholedb&taxa_species=1&redlistCategory%5B%5D=all&country%5B%5D=all&regions%5B%5D=all&aquatic%5B%5D=all&Submit.x=29&Submit.y=10.

NatureServe. 2001. "Chaetodipus baileyi" (On-line). NatureServe Explorer: An online encyclopedia of life. Accessed November 25, 2002 at http://www.natureserve.org/explorer/servlet/NatureServe?menuselect=none&sourceTemplate=tabular_report.wmt&loadTemplate=species_RptComprehensive.wmt&selectedReport=RptComprehensive.wmt&summaryView=tabular_report.wmt&elKey=101724&paging=home&save=true&startIndex=1&nextStartIndex=1&reset=false&offPageSelectedElKey=101724&offPageSelectedElType=species&offPageYesNo=true&post_processes=&radiobutton=radiobutton&selectedIndexes=101724&menuselectfooter=none.

UNEP-WCMC. 2002. "UNEP-WCMC Species Database: Cites-Listed Species" (On-line ). Accessed 11/25/02 at http://valhalla.unep-wcmc.org/isdb/cites/taxonomy/tax-gs-search2.cfm?displaylanguage=eng&GenName=Chaetodipus&SpcName=baileyi&CFNoCache=TRUE.

Brylski, P. 1999. "Bailey's Pocket Mouse" (On-line). California Wildlife Habitat Relationships System. Accessed May 06, 2004 at http://www.dfg.ca.gov/whdab/html/M092.html.

Burt, W., R. Grossenheider. 1980. Peterson field guides: Mammals. New York, New York, USA: Houghton Mifflin Company.

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition. Baltimore and London: The Johns Hopkins University Press.

Paulson, D. 1988. Chaetodipus baileyi. Mammalian Species, 297: 1-5.

Reynolds, H., H. Haskell. 1949. Life history notes on Price and Bailey pocket mice of southern Arizona. Journal of Mammalogy: 150-156.