Great Basin pocket mouse

Great Basin pocket mouse
Conservation status

Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Heteromyidae
Genus: Perognathus
Species: P. parvus
Binomial name
Perognathus parvus
(Peale, 1848)
Synonyms

Perognathus xanthanotus[1]

The Great Basin pocket mouse (Perognathus parvus) is a species of rodent in the family Heteromyidae.[2][3][4][5] It is found in British Columbia in Canada and the western United States.[1]

Taxonomy

There are several subspecies of P. parvus. Sulentich[6] and Genoways and Brown[2] classify the yellow-eared pocket mouse as P. p. xanthonus Grinell, a subspecies of the Great Basin pocket mouse. However, Jones and others[4] classify the yellow-eared pocket mouse as a distinct species, P. xanthonotus (Grinnell).

Distribution

The Great Basin pocket mouse occurs in the Columbia River Basin and the Great Basin and adjacent lands. It is distributed from south-central British Columbia and eastern Washington south to southeastern California, Nevada and northern Arizona, and east to southeastern Montana and Wyoming.[7][8] Distribution of subspecies is:[2][3]

The yellow-eared pocket mouse occurs on the eastern slope of the Tehachapi Mountains in Kern County, California.[3][8] It is not certain whether its distribution is disjunct or joins that of P. parvus olivaceus.[2]

Plant communities

The Great Basin pocket mouse occupies steppes and open, arid shrublands and woodlands. It most commonly occurs in sagebrush (Artemisia spp.), shadscale (Atriplex confertifolia), and other desert shrublands, and in pinyon-juniper (Pinus-Juniperus spp.) woodland. On the eastern slope of the Cascade Range and the Sierra Nevada, it occurs in ponderosa pine (P. ponderosa) and Jeffrey pine (P. jefferyi) woodlands.[2] Riparian zones may have larger concentrations of Great Basin pocket mice than upland areas.[9][10]

Timing of major life events

In late fall and winter, Great Basin pocket mice remain in their burrows in a state of torpor.[11][12] They emerge from their burrows and mate in early spring.[8][11][12] Males emerge slightly before females. In south-central Washington, Great Basin pocket mice emerged from March to April.[13] Prebreeding enlargement of ovaries and testes begins in winter in the complete darkness of the burrow. Following emergence from the burrow, the lengthening photoperiod of spring apparently triggers final enlargement and development of gonads for breeding.[14] Access to succulent green vegetation in spring may enhance reproductive success of females. Captive female Great Basin pocket mice from eastern Washington fed lettuce and seeds had significantly larger ovaries than control females fed only seeds. Great Basin pocket mice remain reproductively active through summer. Females produce one or two litters per year. Most first litters are delivered in May and second litters in August.[8][15] Reports of average litter size have ranged from 3.9 in south-central Washington[15] to 5.6 in Nevada.[16] First-litter subadults first leave the natal burrow in early summer; subadults from the second litter first emerge in fall. In a 2-year study in south-central Washington, first-litter subadults first emerged in June, and second-litter subadults first emerged in October (1974) and November (1975).[13]

As it signals the beginning of the breeding season, photoperiod may often signal its end. In the laboratory, an artificial short day-long night summer photoperiod caused gonadal shrinkage in Great Basin pocket mice. A favorable diet apparently overrides this effect, however, extending the breeding season. In nature, Great Basin pocket mice remain reproductively active through fall in years of favorable plant production. Juveniles typically breed in their second year, but first-litter individuals may first reach breeding condition before winter when plant productivity is high.[14]

Great Basin pocket mice occupy open, arid terrain. They seek friable soil of a variety of textures for burrowing.[17][18][19]

Home ranges of 7,060 to 9,630 square feet (656–895 sq m) have been reported for Great Basin pocket mice in British Columbia. Males may have larger home ranges than females. Average home ranges reported from south-central Washington are 23,030 square feet (2,140 sq m) and 33,640 square feet (3,125 sq m) for adult males and 15,564 square feet (1,446 sq m) for adult females.[15] In big sagebrush habitat on the Malheur National Wildlife Refuge, Oregon, home ranges of adult males were significantly greater (p < 0.001) than home ranges of females. Reproductively active adult males had significantly (p < 0.05) larger home ranges than adult males with unenlarged testes. In black greasewood (Sarcobatus vermiculatus) habitat, however, there were no significant differences between male and female home ranges or between home ranges of reproductive and nonreproductive adult males.[20]

Cover requirements

Great Basin pocket mice are nocturnal and use burrows for daytime cover. They also use burrows during periods of winter and summer torpor.[8][15][21][22] The winter burrow consists of a 3- to 6-foot- (0.9–1.8 m-) deep tunnel leading to a chamber lined with dry vegetation. The summer burrow is shallow. Except for mothers with young, the burrow is occupied by a single individual.[8]

Food habits

Great Basin pocket mice consume primarily seeds, but eat some green vegetation.[11][12] Prior to production of seeds, they also consume insects.[23] Great Basin pocket mice do not use free water,[24] they metabolize water from food.[8] Pocket mice (Perognathus spp.) and other heteromyids are scatterhoarders, caching seeds in shallow depressions and covering the seeds with soil. The seeds are primarily those of grass species, and some preferred forb species. Indian ricegrass (Oryzopsis hymenoides),[25] cheatgrass (Bromus tectorum), Russian-thistle (Salsola kali),[15] antelope bitterbrush (Purshia tridentata), pigweed (Amaranthus spp.), and mustard (Brassica spp.)[8] seeds are important Great Basin pocket mouse food items. In productive years, cheatgrass seeds formed a major portion of the diet of Great Basin pocket mice in southeastern Washington.[15]

Seeds of medusahead (Taeniatherum caput-medusae) were not used by Great Basin pocket mice in Lassen County, California, and areas with heavy medusahead invasion were avoided.[25]

Estimated seed intake of a Great Basin pocket mouse is from 4% to 10% of total body weight daily. Assuming a wholly cheatgrass diet, an individual requires 870 to 1,000 seeds per day in spring and summer, and about 750 seeds per day in fall. Estimated daily maintenance energy requirement ranges from a winter low of 2.4 kilocalories (males) and 2.6 kilocalories (females) to a high of 7.0 kilocalories (males) and 6.6 kilocalories (females) in spring. A total of about 1.8 to 2.1 ounces (50–60 g) of seed must be cached to meet the winter energy requirement.[15] To conserve energy when food is scarce in summer, Great Basin pocket mice often enter a state of torpor that lasts a few hours.[13][15]

Great Basin pocket mice are fairly successful at finding buried seed caches, even those buried by other individuals. In a laboratory experiment, Great Basin pocket mice found Indian ricegrass seeds 17.5% of the time when researchers cached seeds 1.3 centimeters below ground; 42.5% of the time when seeds were cached 0.6 centimeter below ground; and 100% of the time when seeds were scattered on the soil surface.[26]

Predators

Owls (Tytonidae and Strigidae),[8] including Northern Saw-whet Owls (Aegolius acadicus)[9] and Burrowing Owls (Speotyto cunicularia)[27] hawks (Accipitridae),[8] coyotes (Canis latrans),[28][29] foxes (Vulpes and Urocyon spp.), weasels and skunks (Mustelidae), and snakes[8] prey on Great Basin pocket mice.

References

 This article incorporates public domain material from the United States Department of Agriculture document "Perognathus parvus".

  1. ↑ 1.0 1.1 1.2 Linzey, A.V. & NatureServe (Hammerson, G.) (2008). Perognathus parvus. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 22 January 2009. Database entry includes a brief justification of why this species is of least concern
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Williams, Daniel F.; Genoways, Hugh H.; Braun, Janet K. 1993. Taxonomy. In: Genoways, Hugh H.; Brown, James H. (eds.) Biology of the Heteromyidae. Special Publication No. 10. The American Society of Mammalogists: 38–196
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Hall, E. Raymond. 1981. The mammals of North America. 2nd ed. Volume I. New York: John Wiley & Sons
  4. ↑ 4.0 4.1 Jones, J. Knox, Jr.; Hoffmann, Robert S.; Rice, Dale W.; 1992. Revised checklist of North American mammals north of Mexico, 1991. Occasional Papers No. 146. Lubbock, TX: Texas Tech University, The Museum.
  5. ↑ Hafner, John C.; Hafner, Mark S. (1983). "Evolutionary relationships of Heteromyid rodents". Great Basin Naturalist 7: 3–29.
  6. ↑ Sulentich, J. M. 1983. The systematics and evolution of the Perognathus parvus species group in southern California. Long Beach, CA: California State University.
  7. ↑ Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals, reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's associations for the eleven western states. Tech. Note 301. Denver, CO: U.S. Department of the Interior, Bureau of Land Management
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 Whitaker, John O., Jr. (1980). National Audubon Society field guide to North American mammals. New York: Alfred A. Knopf, Inc ISBN 0394507630
  9. ↑ 9.0 9.1 Cannings, Richard J. 1987. The breeding biology of northern saw-whet owls in southern British Columbia. In: Nero, Robert W.; Clark, Richard J.; Knapton, Richard J.; Hamre, R. H., eds. Biology and conservation of northern forest owls: Symposium proceedings; 1987 February 3–7; Winnipeg, MB. Gen. Tech. Rep. RM-142. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 193–198.
  10. ↑ Clary, Warren P.; Medin, Dean E. 1992. Vegetation, breeding bird, and small mammal biomass in two high-elevation sagebrush riparian habitats. In: Clary, Warren P.; McArthur, E. Durant; Bedunah, Don; Wambolt, Carl L., compilers. Proceedings—symposium on ecology and management of riparian shrub communities; 1991 May 29–31; Sun Valley, ID. Gen. Tech. Rep. INT-289. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station: 100–110
  11. ↑ 11.0 11.1 11.2 O'Farrell, Michael J. (1978). "Home range dynamics of rodents in a sagebrush community". Journal of Mammalogy 59 (4): 657–668. doi:10.2307/1380131. JSTOR 1380131.
  12. ↑ 12.0 12.1 12.2 O'Farrell, Thomas P.; Olson, Richard J.; Gilbert, Richard O.; Hedlund, John D. (1975). "A population of Great Basin pocket mice, Perognathus parvus, in the shrub-steppe of south-central Washington". Ecological Monographs 45: 1–28. doi:10.2307/1942329. JSTOR 1942329.
  13. ↑ 13.0 13.1 13.2 Hedlund, J. D.; Rogers, L. E. (1980). "Great Basin pocket mice (Perognathus parvus) in the vicinity of radioactive waste management areas". Northwest Science 54 (2): 153–159.
  14. ↑ 14.0 14.1 Kenagy, G. J.; Barnes, B. M. (1984). "Environmental and endogenous control of reproductive function in the Great Basin pocket mouse Perognathus parvus". Biology of Reproduction 31 (4): 637–645. doi:10.1095/biolreprod31.4.637. PMID 6509135.
  15. ↑ 15.0 15.1 15.2 15.3 15.4 15.5 15.6 15.7 Schreiber, R. Kent (1978). "Bioengergetics of the Great Basin pocket mouse, Perognathus parvus". Acta Theriologica 23 (32): 469–487.
  16. ↑ Hall, E. Raymond. 1946. Mammals of Nevada. Berkeley, CA: University of California Press
  17. ↑ Black, Hal L.; Frischknecht, Neil C. 1971. Relative abundance of mice on seeded sagebrush-grass range in relation to grazing. Res. Note INT-147. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station
  18. ↑ Hedlund, J. D.; Rickard, W. H. (1981). "Wildfire and the short-term response of small mammals inhabiting a sagebrush-bunchgrass community". Murrelet 62: 10–14. doi:10.2307/3534441. JSTOR 3534441.
  19. ↑ Verner, Jared; Boss, Allan S., tech. coords. 1980. California wildlife and their habitats: western Sierra Nevada. Gen. Tech. Rep. PSW-37. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station
  20. ↑ Feldhamer, George A. (1979). "Home range relationships of three rodent species in southeast Oregon". Murrelet 60 (2): 50–57. doi:10.2307/3535769. JSTOR 3535769.
  21. ↑ Maser, Chris; Thomas, Jack Ward; Anderson, Ralph G. 1984. Wildlife habitats in managed rangelands—the Great Basin of southeastern Oregon: The relat. of terrestrial vertebrates to plant communities: Part 2. Appendices. Gen. Tech. Rep. PNW-172. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station; Washington, DC: U.S. Department of the Interior, Bureau of Land Management
  22. ↑ McAdoo, J. Kent; Klebenow, Donald A. 1979. Native faunal relationships in sagebrush ecosystems. In: The sagebrush ecosystem: a symposium: Proceedings; 1978 April; Logan, UT. Logan, UT: Utah State University, College of Natural Resources: 50–61
  23. ↑ Dunigan, P. F. X., Jr.; Lei, W.; Rickard, W. H. (1980). "Pocket mouse population response to winter precipitation and drought". Northwest Science 54 (4): 289–295.
  24. ↑ Price, M. V.; Brown, J. H. (1983). "Patterns of morphology and resource use in North American desert rodent communities". Great Basin Naturalist Memoirs 7: 117–134.
  25. ↑ 25.0 25.1 Longland, William S. 1994. Seed use by desert granivores. In: Monsen, Stephen B.; Kitchen, Stanley G., compilers. Proceedings—ecology and management of annual rangelands; 1992 May 18–22; Boise, ID. Gen. Tech. Rep. INT-GTR-313. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station: 233–237
  26. ↑ Johnson, Terrell K.; Jorgensen, Clive D. (1981). "Ability of desert rodents to find buried seeds". Journal of Range Management 34 (4): 312–314. doi:10.2307/3897858. JSTOR 3897858.
  27. ↑ Henny, Charles J.; Blus, Lawrence J. (1981). "Artificial burrows provide new insight into burrowing owl nesting biology". Raptor Research 15 (3): 82–85.
  28. ↑ Edwards, Loren Lee. 1975. Home range of the coyote in southern Idaho. Pocatello, ID: Idaho State University, Thesis
  29. ↑ Springer, Joseph Tucker (1982). "Movement patterns of coyotes in south central Washington". Journal of Wildlife Management 46 (1): 191–200. doi:10.2307/3808422. JSTOR 3808422.