Great Basin Pocket Mouse
Encyclopedia
The Great Basin Pocket Mouse (Perognathus parvus) is a species of rodent
in the Heteromyidae
family. It is found in British Columbia
in Canada
and the western United States
.
pocket mouse. However, Jones and others classify the yellow-eared pocket mouse as a distinct species, P. xanthonotus (Grinnell).
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
. Distribution of subspecies is:
The yellow-eared pocket mouse occurs on the eastern slope of the Tehachapi Mountains
in Kern County, California
. It is not certain whether its distribution is disjunct
or joins that of P. parvus olivaceus.
s 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. Riparian zones
may have larger concentrations of Great Basin Pocket Mice than upland areas.
. They emerge from their burrows and mate in early spring. Males emerge slightly before females. In south-central Washington, Great Basin Pocket Mice emerged from March to April. 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. 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. Reports of average litter size have ranged from 3.9 in south-central Washington to 5.6 in Nevada. 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).
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.
Great Basin Pocket Mice occupy open, arid terrain. They seek friable soil of a variety of textures for burrowing.
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. 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.
(Salsola kali), antelope bitterbrush
(Purshia tridentata), pigweed (Amaranthus spp.), and mustard
(Brassica spp.) 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.
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.
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. To conserve energy when food is scarce in summer, Great Basin pocket mice often enter a state of torpor that lasts a few hours.
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.
and Strigidae), including Northern Saw-whet Owl
s (Aegolius acadicus) and Burrowing Owl
s (Speotyto cunicularia) hawks (Accipitridae
), coyote
s (Canis latrans), foxes (Vulpes
and Urocyon
spp.), weasel
s and skunk
s (Mustelidae), and snakes prey on Great Basin Pocket Mice.
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
in the Heteromyidae
Heteromyidae
The family of rodents that include kangaroo rats, kangaroo mice and rock pocket mice is the Heteromyidae family. Most heteromyids live in complex burrows within the deserts and grasslands of western North America, though species within the Heteromys and Liomys genera are also found in forests and...
family. It is found in British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
and the western United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
Taxonomy
There are several subspecies of P. parvus. Sulentich and Genoways and Brown classify the yellow-eared pocket mouse as P. p. xanthonus Grinell, a subspecies of the Greatpocket mouse. However, Jones and others classify the yellow-eared pocket mouse as a distinct species, P. xanthonotus (Grinnell).
Distribution
The Great Basin Pocket Mouse occurs in the Columbia River BasinColumbia Basin
The Columbia Basin, the drainage basin of the Columbia River, occupies a large area–about —of the Pacific Northwest region of North America. In common usage, the term often refers to a smaller area, generally the portion of the drainage basin that lies within eastern Washington.Usage of the term...
and the Great Basin
Great Basin
The Great Basin is the largest area of contiguous endorheic watersheds in North America and is noted for its arid conditions and Basin and Range topography that varies from the North American low point at Badwater Basin to the highest point of the contiguous United States, less than away at the...
and adjacent lands. It is distributed from south-central British Columbia and eastern Washington south to southeastern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...
and northern Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, and east to southeastern Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
and Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
. Distribution of subspecies is:
- Perognathus parvus bullatus: (Durrant and Lee) – central and east-central UtahUtahUtah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
- P. p. clarus (Goldman) – extreme southwestern Montana; southeastern IdahoIdahoIdaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....
; extreme north-central Utah; extreme southwestern Wyoming - P. p. columbianus (Merriam) – central and southern Washington
- P. p. idahoensis (Goldman) – south-central Idaho
- P. p. laingi (Anderson) – south-central British Columbia
- P. p. lordi (Gray) – extreme south-central Bristish Columbia; central and eastern Washington; northwestern Idaho
- P. p. mollipilosus (Coues) – south-central Oregon; north-central and northeastern California
- P. p. olivaceus (Merriam) – most of Nevada; eastern California; extreme southeastern Oregon; southern Idaho; western Colorado; the most widely distributed subspecies
- P. p. parvus (Peale) – southeastern Washington; central and eastern Oregon
- P. p. trumbullensis (Benson) – southern ColoradoColoradoColorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
; northern Arizona - P. p. yakimensis (Broadbooks) – south-central Washington
The yellow-eared pocket mouse occurs on the eastern slope of the Tehachapi Mountains
Tehachapi Mountains
The Tehachapi Mountains , regionally also called The Tehachapis, are a mountain range in the Transverse Ranges system of California in the Western United States...
in Kern County, California
Kern County, California
Spreading across the southern end of the California Central Valley, Kern County is the fifth-largest county by population in California. Its economy is heavily linked to agriculture and to petroleum extraction, and there is a strong aviation and space presence. Politically, it has generally...
. It is not certain whether its distribution is disjunct
Disjunct distribution
In biology, a taxon with a disjunct distribution is one that has two or more groups that are related but widely separated from each other geographically...
or joins that of P. parvus olivaceus.
Plant communities
The Great Basin Pocket Mouse occupies steppeSteppe
In physical geography, steppe is an ecoregion, in the montane grasslands and shrublands and temperate grasslands, savannas, and shrublands biomes, characterized by grassland plains without trees apart from those near rivers and lakes...
s and open, arid shrublands and woodlands. It most commonly occurs in sagebrush
Sagebrush
Sagebrush is a common name of a number of shrubby plant species in the genus Artemisia native to western North America;Or, the sagebrush steppe ecoregion, having one or more kinds of sagebrush, bunchgrasses and others;...
(Artemisia spp.), shadscale
Atriplex confertifolia
Atriplex confertifolia is a species of evergreen shrub in the Chenopodiaceae family, which is native to the western United States.-Habitat:Shadscale is a common, often dominant, shrub in the lowest and driest areas of the Great Basin...
(Atriplex confertifolia), and other desert shrublands, and in pinyon-juniper (Pinus-Juniperus spp.) woodland. On the eastern slope of the Cascade Range
Cascade Range
The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...
and the Sierra Nevada, it occurs in ponderosa pine (P. ponderosa) and Jeffrey pine
Jeffrey Pine
The Jeffrey Pine, Pinus jeffreyi, named in honor of its botanist documenter John Jeffrey, is a North American pine related to Ponderosa Pine.-Distribution and habitat:...
(P. jefferyi) woodlands. Riparian zones
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
may have larger concentrations of Great Basin Pocket Mice than upland areas.
Timing of major life events
In late fall and winter, Great Basin Pocket Mice remain in their burrows in a state of torporTorpor
Torpor, sometimes called temporary hibernation is a state of decreased physiological activity in an animal, usually characterized by a reduced body temperature and rate of metabolism. Animals that go through torpor include birds and some mammals such as mice and bats...
. They emerge from their burrows and mate in early spring. Males emerge slightly before females. In south-central Washington, Great Basin Pocket Mice emerged from March to April. Prebreeding enlargement of ovaries
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
and testes
Testicle
The testicle is the male gonad in animals. Like the ovaries to which they are homologous, testes are components of both the reproductive system and the endocrine system...
begins in winter in the complete darkness of the burrow. Following emergence from the burrow, the lengthening photoperiod
Photoperiodism
Photoperiodism is the physiological reaction of organisms to the length of day or night. It occurs in plants and animals.Photoperiodism can also be defined as the developmental responses of plants to the relative lengths of the light and dark periods...
of spring apparently triggers final enlargement and development of gonads for breeding. Access to succulent green vegetation in spring may enhance reproductive success
Reproductive success
Reproductive success is defined as the passing of genes onto the next generation in a way that they too can pass those genes on. In practice, this is often a tally of the number of offspring produced by an individual. A more correct definition, which incorporates inclusive fitness, is the...
of females. Captive female Great Basin Pocket Mice from eastern Washington fed lettuce
Lettuce
Lettuce is a temperate annual or biennial plant of the daisy family Asteraceae. It is most often grown as a leaf vegetable. It is eaten either raw, notably in salads, sandwiches, hamburgers, tacos, and many other dishes, or cooked, as in Chinese cuisine in which the stem becomes just as important...
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. Reports of average litter size have ranged from 3.9 in south-central Washington to 5.6 in Nevada. 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).
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.
Great Basin Pocket Mice occupy open, arid terrain. They seek friable soil of a variety of textures for burrowing.
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. In big sagebrush
Artemisia tridentata
Artemisia tridentata is a shrub or small tree from the family Asteraceae. Some botanists treat it in the segregate genus Seriphidium, as S. tridentatum W. A. Weber, but this is not widely followed...
habitat on the Malheur National Wildlife Refuge
Malheur National Wildlife Refuge
Malheur National Wildlife Refuge is located roughly south of the town of Burns, Oregon. The refuge area is roughly T shaped with the southernmost base at Frenchglen, the left top at Malheur Lake and the right top at Harney Lake....
, 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
Greasewood
Greasewood, Sarcobatus, is a genus of one or two species of flowering plants. Traditionally it has been treated in the family Chenopodiaceae, but the APG II system, of 2003, places it in the family Sarcobataceae....
(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.
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. 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.Food habits
Great Basin Pocket Mice consume primarily seeds, but eat some green vegetation. Prior to production of seeds, they also consume insects. Great Basin Pocket Mice do not use free water, they metabolize water from food. 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), cheatgrass (Bromus tectorum), Russian-thistleSalsola kali
Kali soda is an annual plant that grows in arid soils and in sandy coastal soils. Its original range is Eurasian, but it has become naturalized, and even invasive, in North America, Australia, and elsewhere...
(Salsola kali), antelope bitterbrush
Purshia tridentata
Purshia tridentata is a nitrogen fixing shrub in the genus Purshia, native to mountainous areas of western North America ranging from southeastern British Columbia in the north, east to Montana and south to California and New Mexico...
(Purshia tridentata), pigweed (Amaranthus spp.), and mustard
Brassica
Brassica is a genus of plants in the mustard family . The members of the genus may be collectively known either as cabbages, or as mustards...
(Brassica spp.) 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.
Seeds of medusahead
Taeniatherum caput-medusae
Taeniatherum caput-medusae is a species of grass known by the common name medusahead. This aggressive winter annual grass is changing the ecology of western rangelands in North America. Forty-eight percent of the total land area of the United States is rangeland, pastureland, national parks, nature...
(Taeniatherum caput-medusae) were not used by Great
Basin pocket mice in Lassen County, California
Lassen County, California
Lassen County is a county located in the northeastern portion of the U.S. state of California. As of the 2010 census, the population was 34,895, up from 33,828 at the 2000 census...
, and areas with heavy medusahead invasion were avoided.
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. To conserve energy when food is scarce in summer, Great Basin pocket mice often enter a state of torpor that lasts a few hours.
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.
Predators
Owls (TytonidaeTytonidae
Barn-owls are one of the two families of owls, the other being the true owls, Strigidae. They are medium to large sized owls with large heads and characteristic heart-shaped faces. They have long, strong legs with powerful talons...
and Strigidae), including Northern Saw-whet Owl
Northern Saw-whet Owl
The Northern Saw-whet Owl is a small owl native to North America.-Description:The scientific description of one of the sub-species of this owl is attributed to the Rev. John Henry Keen who was a missionary in Canada in 1896. Adults are long with a wingspan. They can weigh from with an average...
s (Aegolius acadicus) and Burrowing Owl
Burrowing Owl
The Burrowing Owl is a tiny but long-legged owl found throughout open landscapes of North and South America. Burrowing Owls can be found in grasslands, rangelands, agricultural areas, deserts, or any other open dry area with low vegetation. They nest and roost in burrows, such as those excavated...
s (Speotyto cunicularia) hawks (Accipitridae
Accipitridae
The Accipitridae, one of the two major families within the order Accipitriformes , are a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a...
), coyote
Coyote
The coyote , also known as the American jackal or the prairie wolf, is a species of canine found throughout North and Central America, ranging from Panama in the south, north through Mexico, the United States and Canada...
s (Canis latrans), foxes (Vulpes
Vulpes
Vulpes is a genus of the Canidae family. Its members are referred to as 'true foxes', although there are species in other genera whose common names include the word 'fox'....
and Urocyon
Urocyon
The genus Urocyon is a genus that contains two living Western Hemisphere foxes in the family Canidae, the Gray Fox and the closely related Island Fox which is a dwarf cousin of the Gray Fox; as well as one fossil species, Urocyon progressus.Urocyon and the...
spp.), weasel
Weasel
Weasels are mammals forming the genus Mustela of the Mustelidae family. They are small, active predators, long and slender with short legs....
s and skunk
Skunk
Skunks are mammals best known for their ability to secrete a liquid with a strong, foul odor. General appearance varies from species to species, from black-and-white to brown or cream colored. Skunks belong to the family Mephitidae and to the order Carnivora...
s (Mustelidae), and snakes prey on Great Basin Pocket Mice.