Chaetodipus formosus

Geographic Range

Chaetodipus formosus is found in the western United States including southern Nevada, western Utah, southeastern California into the Baja peninsula, and the northwest corner of Arizona. Chaetodipus formosus also is found in Northern Mexico.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Chaetodipus formosus occupies a wide variety of elevations, from 85 m below sea level to 1,970 meters above. They are most often found in rocky desert areas that contain sagebrush, desert scrub, and desert succulent shrubs with hard groundcover and/or rocky soils. These areas are often at the base of cliffs or at the mouth of canyons. They are found in the lava beds of Vulcan's Throne, on rocky or gravelly soil of dry stream beds, or among marble-sized rocks of the desert scrub floor and Colorado River beaches.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune

Physical Description

Body length of these animals is between 76 and 101 mm, with a crested tail usually adding 80 to 110 mm in length. They weigh between 10.5 and 17 grams. The dorsal pelage is grey with a white underside. Chaetodipus formosus has the same dental formula as all heteromyids: I 1/1, C 0/0, P 1/1, M 3/3 X 2 = 20

• Other Physical Features
• endothermic endothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

The is no information found on the mating systems of long-tailed pocket mice

Chaetodipus formosus is an iteroparous species breeding more than once in its life time. The breeding season occurs in the spring lasting about four months with a peak in the middle two months. Populations can increase rapidly, and under good conditions up to 70 per cent of the females in the population will become pregnant. With an average litter size just under 6 young, this can lead to up to a five fold increase in population size. In years with good precipitation and food suppy a second breeding season may occur, and those young born early in the year are able to reproduce by this second season.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• viviparous viviparous

There is no information on the parental care of C. formosus . However, most small mice are altricial when they are born. Mothers typically care for the young in a nest of some sort until they are able to walk about. Most parental care in mice is provided by females, who groom, nurse, and protect the young. No information is available on the extent of male parental care in this species.

• Parental Investment
• no parental involvement
• altricial altricial
• pre-fertilization
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • protecting
    • female

Lifespan/Longevity

No information could be found on the lifespan of long-tailed pocket mice, but generally pocket mice only live 1 to 2 years.

Behavior

Distribution and abundance seem to depend on soil characteristics rather than on characteristics of the shrub cover. Long-tailed pocket mice are found a variety of desert shrub species which provide sparse to dense cover for the mice. They are nocturnal, active on the surface throughout much of the year with exception of late fall through early spring. Below-ground activity and aestivation is related to periods of cold weather, with increasing above-ground ambient temperatures accompanied by increasing activity. In summer, 30 to 40% of time is spent above-ground Daily cycles involve bursts of activity shortly after sunset for 2 hr followed by a cessation of activity at 6 hr after sunset. Burrows are excavated in gravelly or rocky banks, or at base of shrubs. The species is solitary, and aggressively maintains a territory. Competition for food has also been documented.

• Key Behaviors
• terricolous
• fossorial fossorial
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• aestivation
• solitary solitary

Home Range

Males have larger home range than females, and range size is inversely related to population density. In the Mojave desert, the average size of the home range was 0.55 hectares.

Communication and Perception

No information could be found on the communication techniques of C. formosus . However, as mammals, they are able to perceive visual stimuli, and have senses of smell and taste. It is likely that these senses are involved in communication. Tactile communication is probably important between mates, rivals, or between mother and offspring.

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Chaetodipus formosus has external fur lined cheek pouches to carry seed and other food items. Seed caching and food storage is common among the family Heteromyidae. Although this species is primarily granivorous, they also eat fruits and arthropods, and feed opportunistically on stems and leaves of green vegetation. Seeds are collected on the ground beneath and between shrubs, and on rocky surfaces. Water is obtained from food, especially green vegetation.

• Primary Diet
• herbivore herbivore
  • granivore granivore

• Animal Foods
• insects
• terrestrial non-insect arthropods

• Plant Foods
• leaves
• seeds, grains, and nuts
• fruit

• Foraging Behavior
• stores or caches food stores or caches food

Predation

Predators include owls, snakes, leopard lizards, swift foxes, and other predatory mammals.

Ecosystem Roles

Burrows are excavated in gravely or rocky banks, or at the base of shrubs. This provides aeration of the soil because they are burrowing and turning up the soil. As seed cachers, they probably help to disperse seeds. Because they are a prey species, it is likely they could affect predator populations--especially in years where reproduction is high.

• Ecosystem Impact
• disperses seeds
• soil aeration soil aeration

Economic Importance for Humans: Positive

No information was found on positive economic impacts of long-tailed pocket mice.

Economic Importance for Humans: Negative

Burrowing could be a potential conflict for farmers if the species is creating burrows in farm fields. Heteromyid rodents are also reservoirs for many zoonotic diseases.

• Negative Impacts
• injures humans
  • carries human disease
• crop pest
• causes or carries domestic animal disease causes or carries domestic animal disease

Conservation Status

Long-tailed pocket mice are not listed by IUCN or CITES.

Other Comments

Until recently, this species was refered to as Perognathus . Hafner suggested that, based on morphological and other characters, spiny perognathine pocket mice merited the elevation of the subgenus Chaetodipus to full generic status.

Additional Links

Encyclopedia of Life

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Amanda Eckhart (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.

References

Brylski, P. 1999. "Long tailed Pocket Mouse" (On-line). California Wildlife Habitat Relationships System. Accessed March 29, 2004 at http://www.dfg.ca.gov/whdab/html/M091.html .

Geluso, K. 1999. Long-tailed pocket mouse ( Chaetodipus formosus ). Pp. 511-512 in The Smithsonian Book of North American Mammals . Washington, D.C.: Smithsonian Institution Press.

Guinn, E. 2002. "Long-tailed pocket mouse" (On-line). Utah Division of Wildlife Resources. Accessed March 29, 2004 at http://dwrcdc.nr.utah.gov/rsgis2/Search/Display.asp?FlNm=chaeform .

Hafner, J. 1983. Evolutionary Relationships of Heteromyid Rodents. Great Basin Naturalist Memoirs , 7: 3-29.

Jenkins, S., S. Breck. 1998. Differences in Food Hoarding Among Six Species Of Heteromyid Rodents. Journal of Mammalogy , 79: 1221-1232.

Price, M., N. Waser, S. McDonald. 2002. Seed Caching By Heteromyid Rodents From Two Communities: Implications for Coexistence. Journal of Mammalogy , 81: 97-106.

The New Mexico Department of Game & Fish. 2004. "Long-tailed pocket mouse" (On-line). Biota Information System Of New Mexico. Accessed March 29, 2004 at http://fwie.fw.vt.edu/states/nmex_main/species/050436.htm .