Animal Diversity Web

Ge­o­graphic Range

Pinyon mice can be found as far east as the pan­han­dle of north Texas and as far west as the Pa­cific coast. The north­ern limit of their range is cen­tral Ore­gon, and the south­ern limit is south­ern Mex­ico. (Hoffmeis­ter, et al., 1981; Wil­son and Ruff, 1999)

• Biogeographic Regions
• nearctic
  • native
• neotropical
  • native

Habi­tat

Pinyon mice are ter­res­trial mam­mals that can be found at al­ti­tudes rang­ing from sea level to el­e­va­tions of greater than 2300 me­ters. They fre­quent arid or semi-arid cli­mates, pre­fer­ring brush­land and desert, and are typ­i­cally found near pinyon ju­nipers, hence their com­mon name. How­ever, pinyon mice can also be found in open, grassy habi­tats, as well as land­scapes in­clud­ing canyons, red­woods, yel­low pine belts, sage­brush, scrub oak, boul­ders, cacti, and rocky slopes. Pinyon mice are able to en­dure warm, dry sum­mers in ad­di­tion to snowy win­ters. They make dens under rock ledges, out­crops, stone shelves and slabs, and in live or dead trees. (Hall and Mor­ri­son, 1997; Hoffmeis­ter, et al., 1981; King, 1968; Wil­son and Ruff, 1999)

• Habitat Regions
• temperate
• terrestrial

• Terrestrial Biomes
• desert or dune
• savanna or grassland
• forest
• scrub forest
• mountains

• Range elevation

  0 to greater than 2300 m

  0.00 to ft

Phys­i­cal De­scrip­tion

Pinyon mice have long, silky fur that ranges from yel­low-brown to dark gray on the back and fades to white on the under parts and feet. They may or may not have a pec­toral spot. The tail is tipped with long hairs and has a dark dor­sal stripe run­ning down its length. The hind feet are large, and are typ­i­cally 22 mm or more in length. Ju­ve­niles have gray pelage that changes with a se­ries of molts, start­ing at 7 weeks and fin­ish­ing at 10 to 11 weeks of age. Coat color matches the habi­tat re­gion­ally, al­low­ing these mice to blend into veg­e­ta­tion and hide from preda­tors. Males and fe­males are sim­i­lar in size, the av­er­age weight is about 20 g, and the head and body length ranges be­tween 171 to 231 mm. Tail length varies from 76 to 123 mm. The size of pinyon mice often varies with lo­ca­tion; pinyon mice in the west­ern parts of their range tend to have a longer tail, smaller body size, smaller ears, and smaller hind feet than their coun­ter­parts in the east. (Hoffmeis­ter, et al., 1981; King, 1968; Wil­son and Ruff, 1999)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike

• Average mass

  20 g

  0.70 oz

• Average mass

  25 g

  0.88 oz

  AnAge

• Range length

  171 to 231 mm

  6.73 to 9.09 in

• Average basal metabolic rate

  0.307 W

  AnAge

Re­pro­duc­tion

Pinyon mice have a promis­cu­ous mat­ing sys­tem in which fe­males nest in small ter­ri­to­ries and males seek mat­ing op­por­tu­ni­ties with nearby fe­males. (Rib­ble and Stan­ley, 1998)

• Mating System
• polygynandrous (promiscuous)

Al­though mat­ing can occur in all sea­sons, pinyon mice breed pri­mar­ily from mid-Feb­ru­ary to mid-No­vem­ber with a peak be­tween April and June. Fe­males give birth to a lit­ter of three to six pups after a ges­ta­tion pe­riod of ap­prox­i­mately 26 days, though ges­ta­tion may be as long as 40 days if the fe­male is lac­tat­ing. Fe­males first come into es­trus at ap­prox­i­mately 50 days of age, and males are ca­pa­ble of in­sem­i­nat­ing fe­males at ap­prox­i­mately 9 weeks of age. (Hoffmeis­ter, et al., 1981; King, 1968; Scheibe and O'Far­rell, 1995; Scheibe, 1984; Wil­son and Ruff, 1999)

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

• Breeding interval

  Pinyon mice breed at intervals as frequent as once monthly.

• Breeding season

  Pinyon mice will breed at any time between February and mid-November with a peak between April and June.

• Range number of offspring

  3 to 6

• Average number of offspring

  3.4

  AnAge

• Range gestation period

  40 (high) days

• Average gestation period

  26 days

• Range weaning age

  3 to 4 weeks

• Range time to independence

  3 to 4 weeks

• Average age at sexual or reproductive maturity (female)

  50 days

• Average age at sexual or reproductive maturity (female)
  Sex: female

  50 days

  AnAge

• Average age at sexual or reproductive maturity (male)

  9 weeks

New­born pinyon mice weigh around 2.3 grams at birth, and they are born com­pletely hair­less with their ears and eyes folded shut. The pups are ca­pa­ble of squeak­ing at one week of age, and their bod­ies are cov­ered in hair by day 14. The pups nurse for three to four weeks, at which point they be­come in­de­pen­dent. Fe­males ex­clu­sively care for their young in a nest until they are weaned. (Wil­son and Ruff, 1999)

• Parental Investment
• altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female

Lifes­pan/Longevity

The lifes­pan of pinyon mice and other mice in the genus Per­omyscus has not been stud­ied in de­tail. An in­di­vid­ual Per­omyscus man­ic­u­la­tus lived to be eight years old in cap­tiv­ity, but stud­ies have shown that mice in this genus rarely live more than a year in the wild. Only 20% of the young in each nest will sur­vive their first year of life, and only 2-3% of adults live long enough to breed in con­sec­u­tive sea­sons. (Hoffmeis­ter, et al., 1981; King, 1968)

• Average lifespan
  Status: wild

  1 years

• Average lifespan
  Status: captivity

  5.4 years

  AnAge

Be­hav­ior

Pinyon mice are noc­tur­nal ro­dents that sleep pe­ri­od­i­cally through­out the day. They are ex­cel­lent climbers, fre­quently using their long tails for bal­ance. Stud­ies have shown that pinyon mice are more ac­tive for­agers when am­bi­ent tem­per­a­tures are higher. Pinyon mice are less ac­tive on moon­lit nights, most likely be­cause there is an in­creased risk of pre­da­tion when it is brighter out­side. In times of se­vere drought, pinyon mice can in­crease urine con­cen­tra­tion, re­duce the mois­ture con­tent of their feces, and drop into a di­ur­nal tor­por to save en­ergy. (Hall and Mor­ri­son, 1997; Hoffmeis­ter, et al., 1981; King, 1968; Rib­ble and Stan­ley, 1998; Scheibe and O'Far­rell, 1995; Scheibe, 1984)

• Key Behaviors
• scansorial
• terricolous
• nocturnal
• motile
• sedentary
• aestivation
• solitary
• territorial

Home Range

Pinyon mice fre­quently use mul­ti­ple den sites dur­ing the day. Male dens are typ­i­cally far­ther apart from each other than fe­male dens, but the ter­ri­to­ries of males tend to over­lap each other more than the ter­ri­to­ries of fe­males. In gen­eral, male ter­ri­to­ries are larger, while fe­male ter­ri­to­ries are smaller be­cause fe­males are con­strained to their dens dur­ing breed­ing. This re­pro­duc­tive con­straint is the basis for their promis­cu­ous mat­ing sys­tem in which males must search for fe­males. (Hall and Mor­ri­son, 1997; Hoffmeis­ter, et al., 1981; King, 1968; Rib­ble and Stan­ley, 1998; Scheibe and O'Far­rell, 1995; Scheibe, 1984)

Com­mu­ni­ca­tion and Per­cep­tion

Com­mu­ni­ca­tion in pinyon mice hasn't been well-stud­ied. They are likely to use vi­sual, au­di­tory, chem­i­cal, and tac­tile modes of com­mu­ni­ca­tion.

Per­omyscus species are known for their acute senses of hear­ing and smell, which they use to nav­i­gate, find food, and es­cape pre­da­tion at night. Their en­larged eyes sug­gest they have a well-de­vel­oped sense of vi­sion in low light con­di­tions. Their long whiskers are used for tac­tile per­cep­tion.

• Communication Channels
• visual
• tactile
• acoustic
• chemical

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Pinyon mice are pri­mar­ily fru­giv­o­rous and graniv­o­rous, al­though they will also read­ily eat in­sects, spi­ders, and other in­ver­te­brates. Adults typ­i­cally feed on ju­niper seeds (Ju­nipe­rus) and berries in the win­ter and acorn mast (Quer­cus) in the sum­mer. Pinyon mice are no­to­ri­ous at caching their food sup­ply; they fre­quently dig holes and bury their food in var­i­ous places around their ter­ri­tory, par­tic­u­larly around den sites. These cache net­works may be­come quite ex­ten­sive. Fi­nally, pinyon mice are ca­pa­ble of sur­viv­ing on a very lim­ited water sup­ply, which is cru­cial to their sur­vival in the arid habi­tats they oc­cupy. (Hoffmeis­ter, et al., 1981; King, 1968; Wil­son and Ruff, 1999)

• Primary Diet
• herbivore
  • granivore

• Animal Foods
• insects
• terrestrial non-insect arthropods

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

• Foraging Behavior
• stores or caches food

Pre­da­tion

Pre­da­tion on pinyon mice has not been well stud­ied, al­though pre­da­tion most likely plays a role in the high mor­tal­ity rate of these ro­dents. Their pri­mary preda­tors are owls, di­ur­nal birds of prey, and snakes, es­pe­cially rat­tlesnakes. They es­cape pre­da­tion by re­main­ing in­ac­tive dur­ing the day in dens, by their cryp­tic col­oration, and by their acute senses at night. (King, 1968)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • owls (Strigiformes)
  • diurnal birds of prey (Falconiformes)
  • rattlesnakes (Crotalus)

Ecosys­tem Roles

Pinyon mice are al­most al­ways found near pinyon ju­nipers, hence their com­mon name. Ju­niper seeds are the main food source of pinon mice, mak­ing them, like other mem­bers of the genus Per­omyscus, sig­nif­i­cant preda­tors of conifer seeds. Thus they im­pact their com­mu­ni­ties by im­pact­ing the com­po­si­tion of the plant com­mu­nity. Their seed caching be­hav­ior may also re­sult in ger­mi­na­tion of seeds. Pinyon mice are also an im­por­tant and abun­dant source of prey for many avian and mam­malian preda­tors. (King, 1968)

• Ecosystem Impact
• disperses seeds

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

It is not known whether pinyon mice have pos­i­tive af­fects on human pop­u­la­tions, aside from their im­por­tant ecosys­tem roles.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Pinyon mice serve as an im­por­tant reser­voir for sev­eral types of par­a­sites. Some have spec­u­lated that they are ca­pa­ble of car­ry­ing plague-in­fested fleas, but this has not been well doc­u­mented. Mem­bers of the genus Per­omyscus are ca­pa­ble of car­ry­ing chig­gers, a com­mon pest, as well as the ticks that trans­mit Rocky Moun­tain Spot­ted Fever and Lyme dis­ease to hu­mans. Per­omyscus species are also im­por­tant reser­voirs for han­taviruses. (King, 1968)

• Negative Impacts
• injures humans
  • carries human disease

Con­ser­va­tion Sta­tus

Pinyon mice are not cur­rently threat­ened through­out much of their range. How­ever, since pinyon ju­nipers are a cru­cial part of their habi­tat, de­struc­tion of such habi­tats can im­peril these mice. The sub­species Per­omyscus truei co­manche, found in the pand­han­dle of north­west­ern Texas, is con­sid­ered near threat­ened by the IUCN. (King, 1968)

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Federal List

  No special status

• CITES

  No special status

Con­trib­u­tors

Tanya Dewey (ed­i­tor), An­i­mal Di­ver­sity Web.

Jen­nifer Gumas (au­thor), Michi­gan State Uni­ver­sity, Bar­bara Lun­dri­gan (ed­i­tor), Michi­gan State Uni­ver­sity.

Ref­er­ences

Hall, L., M. Mor­ri­son. 1997. Den and Re­lo­ca­tion Site Char­ac­ter­is­tics and Home Ranges of <<Per­omyscus truei>> in the White Moun­tains of Cal­i­for­nia. Great Basin Nat­u­ral­ist, 57 (2): 124-130.

Hoffmeis­ter, D., D. Williams, S. An­der­son, T. Lawlor. 1981. Mam­malian Species #161: <<Per­omyscus truei>>. Pp. 1-5 in Mam­malian Species, Vol. 151-200. The Amer­i­can So­ci­ety of Mam­mal­o­gists.

King, J. 1968. Bi­ol­ogy of <<Per­omyscus>> (Ro­den­tia). The United States of Amer­ica: The Amer­i­can So­ci­ety of Mam­mal­o­gists.

Rib­ble, D., S. Stan­ley. 1998. Home Ranges and So­cial Or­ga­ni­za­tion of Syn­topic <<Per­omyscus boylii>> and <<P. truei>>. Jour­nal of Mam­mal­ogy, 79 (3): 932-941.

Scheibe, J. 1984. The Ef­fects of Weather, Sex, and Sea­son on the Noc­tur­nal Ac­tiv­ity of <<Per­omyscus truei>> (Ro­den­tia). The South­west­ern Nat­u­ral­ist, 29 (1): 1-4.

Scheibe, J., M. O'Far­rell. 1995. Habi­tat Dy­nam­ics in <<Per­omyscus truei>>: Eclec­tic Fe­males, Den­sity De­pen­dence, or Re­pro­duc­tive Con­straints?. Jour­nal of Mam­mal­ogy, 76 (2): 368-375.

Wil­son, D., S. Ruff. 1999. The Smith­son­ian Book of North Amer­i­can Mam­mals. Wash­ing­ton and Lon­don: Smith­son­ian In­sti­tu­tion Press.