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Perognathinae is a
subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoolog ...
of
rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are nat ...
s consisting of two genera of pocket mice. Most species live in complex burrows within the
desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
s and
grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge ( Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natu ...
s of western
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the C ...
, They feed mostly on
seed A seed is an Plant embryogenesis, embryonic plant enclosed in a testa (botany), protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, includ ...
s and other plant parts, which they carry in their fur-lined
cheek pouch Cheek pouches are pockets on both sides of the head of some mammals between the jaw and the cheek. They can be found on mammals including the platypus, some rodents, and most monkeys, as well as the marsupial koala. The cheek pouches of chipm ...
es to their burrows.


Description

There are about twenty-six members of the subfamily Perognathinae divided among two
genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomencl ...
. They are all small rodents. Adaptations include partially fused vertebrae in the neck, short fore limbs and much enlarged bullae (bubble-shaped bones in the skull). The dental formula is 1/1, 0/0, 1/1, 3/3 making twenty teeth in total. The molars have two-lobed cusps. The upper incisors are grooved and the enamel on the molars is quickly worn away by chewing leaving the dentine exposed. The check teeth have roots. Fur-lined cheek pouches are a feature across the family Heteromyidae. They have openings near the mouth and extend backwards along the sides of the neck. The fur on the animal's body is in general short and fine and often matches in colour the soil of the region in which the animal lives, being some shade of buff, pale brown, reddish-brown or grey.


Distribution

Pocket mice are distributed from southwestern Canada through the western and Great Plains regions of the United States to central Mexico. They are creatures of open country, mostly specialising in prairies, arid lands and desert fringes.


Behaviour

Pocket mice are adapted for life in deserts and other arid environments where they largely feed on dry seeds. They carry most of the seeds they find back to their burrows in exterior cheek folds lined with fur rather than in cheek pouches inside the mouth as do
hamster Hamsters are rodents (order Rodentia) belonging to the subfamily Cricetinae, which contains 19 species classified in seven genera.Fox, Sue. 2006. ''Hamsters''. T.F.H. Publications Inc. They have become established as popular small pets. The ...
s. This is because carrying the food in the mouth would involve wetting it and moisture needs to be conserved as much as possible in dry environments. Most species store the seeds they gather in special chambers in the burrow where they absorb moisture from the humid air. It has been found that there is little hoarding done in the winter but that food is most commonly stored in the autumn and spring. Heteromyds use sight and olfactory clues to locate possible food and then use their fore-feet to manipulate objects. Pocket mice hunt around under vegetation or debris for individual food items. It has been found that they forage more efficiently than
kangaroo rat Kangaroo rats, small mostly nocturnal rodents of genus ''Dipodomys'', are native to arid areas of western North America. The common name derives from their bipedal form. They hop in a manner similar to the much larger kangaroo, but developed thi ...
s and this is thought to be due to the fact that they handle their finds more and are better able to distinguish between food and non-food items. These animals excavate long burrow systems with passages, chambers and multiple entrances. They are largely
nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...
, feeding and moving about at night and resting deep in their burrows during the day. Here it is cooler and more humid which conserves moisture and the animals may temporarily block the entrances to augment this. They are able to concentrate their
urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellular m ...
to a viscous consistency which further reduces water loss. Under extreme conditions, some are able to
aestivate Aestivation ( la, aestas (summer); also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a ...
in chambers under ground. Pocket mice normally run around on four limbs but can also move with leaps.


Ecology

Pocket mice are eaten by foxes, coyotes, snakes and birds. They have acute hearing and can detect the approaching swoop of an owl or the movements of a snake. Many can leap to avoid the predators as they seek the safety of their burrows. In the
Sonoran Desert The Sonoran Desert ( es, Desierto de Sonora) is a desert in North America and ecoregion that covers the northwestern Mexican states of Sonora, Baja California, and Baja California Sur, as well as part of the southwestern United States (in Arizona ...
there are many closely related species of heteromyid mice and rats. Each has its own niche in the environment which means that they do not unnecessarily compete with each other for the limited available resources. Bailey's pocket mouse climbs into plants and bushes in order to find seeds and berries still attached to the plant. It is the only species able to eat the wax found inside the seeds of the
jojoba Jojoba (; botanical name: ''Simmondsia chinensis'')also commonly called goat nut, deer nut, pignut, wild hazel, quinine nut, coffeeberry, and gray box bushis native to the Southwestern United States. ''Simmondsia chinensis'' is the sole specie ...
plant. The desert pocket mouse forages across the open desert floor and gathers seeds that have fallen to the ground.


Taxonomy

Perognathinae is the
sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...
of
Heteromyinae Heteromyinae is a subfamily of rodents in the family Heteromyidae, commonly known as spiny pocket mice. It contains a single extant genus, ''Heteromys'', as well as the extinct genera '' Diprionomys'' and '' Metaliomys''. ''Heteromys'' was recen ...
; the two are estimated to have split about 22-23 million years ( Ma) ago. The most recent common ancestor of extant Perognathinae species is thought to have lived 20-21 Ma ago, when the two genera split. The most recent common ancestors of extant members of ''Chaetodipus'' and ''Perognathus'' are thought to have lived 14-15 and 17-18 Ma ago, respectively. *Subfamily Perognathinae — pocket mice **Genus ''
Chaetodipus ''Chaetodipus'' is a genus of pocket mouse containing 17 species endemic to the United States and Mexico. Like other members of their family such as pocket mice in the genus ''Perognathus'', they are more closely related to pocket gophers than ...
'' ***
Little desert pocket mouse The little desert pocket mouse (''Chaetodipus arenarius'') is a species of small rodent in the family Heteromyidae. It is endemic to Baja California in Mexico. Description The little desert pocket mouse reaches a length of about including a tai ...
, ''Chaetodipus arenarius'' ***
Narrow-skulled pocket mouse The narrow-skulled pocket mouse (''Chaetodipus artus'') is a species of rodent in the family Heteromyidae. It is endemic to western Mexico, living west of the Sierra Madre Occidental crest. Description The narrow-skulled pocket mouse is a medium ...
, ''Chaetodipus artus'' *** Bailey's pocket mouse, ''Chaetodipus baileyi'' *** California pocket mouse, ''Chaetodipus californicus'' ***
Dalquest's pocket mouse Dalquest's pocket mouse (''Chaetodipus dalquesti'') is a species of rodent in the family Heteromyidae, sometimes viewed as a subspecies of '' Chaetodipus ammophilus''. It is endemic to Mexico. The pocket mouse is named after Walter W. Dalquest (1 ...
, ''Chaetodipus dalquesti'' *** Chihuahuan pocket mouse, ''Chaetodipus eremicus'' *** San Diego pocket mouse, ''Chaetodipus fallax'' *** Long-tailed pocket mouse, ''Chaetodipus formosus'' *** Goldman's pocket mouse, ''Chaetodipus goldmani'' ***
Hispid pocket mouse The hispid pocket mouse (''Chaetodipus hispidus'') is a large pocket mouse native to the Great Plains region of North America. It is a member of the genus ''Chaetodipus''. Distribution The hispid pocket mouse occurs across the Great Plains fro ...
, ''Chaetodipus hispidus'' *** Rock pocket mouse, ''Chaetodipus intermedius'' *** Lined pocket mouse, ''Chaetodipus lineatus'' *** Nelson's pocket mouse, ''Chaetodipus nelsoni'' *** Desert pocket mouse, ''Chaetodipus penicillatus'' *** Sinaloan pocket mouse, ''Chaetodipus pernix'' *** Baja pocket mouse, ''Chaetodipus rudinoris'' ***
Spiny pocket mouse The spiny pocket mouse (''Chaetodipus spinatus'') is a species of rodent in the family Heteromyidae and order Rodentia. It is found in Baja California in Mexico and in Arizona, California and Nevada. Description The spiny pocket mouse has long ...
, ''Chaetodipus spinatus'' **Genus ''
Perognathus ''Perognathus'' is a genus of pocket mouse. Like other members of their family they are more closely related to pocket gophers than to true mice. Characteristics The silky pocket mice are small animals with soft pelage, long tails, and small ...
'' ***
White-eared pocket mouse The white-eared pocket mouse (''Perognathus alticolus'') is a species of rodent in the family Heteromyidae. It is endemic to the San Bernardino Mountains and the Tehachapi Mountains of southern California in the United States. There are two subs ...
, ''Perognathus alticola'' *** Arizona pocket mouse, ''Perognathus amplus'' *** Olive-backed pocket mouse, ''Perognathus fasciatus'' *** Plains pocket mouse, ''Perognathus flavescens'' ***
Silky pocket mouse The silky pocket mouse (''Perognathus flavus'') is a species of rodent in the family Heteromyidae. It is found in northern and central Mexico and the southwest region of the United States. It is a species of least concern, according to the IUCN, ...
, ''Perognathus flavus'' *** San Joaquin pocket mouse, ''Perognathus inornatus'' ***
Little pocket mouse The little pocket mouse (''Perognathus longimembris'') is a species of rodent in the family Heteromyidae. It is found in Baja California and Sonora in Mexico and in Arizona, California, Idaho, Nevada, Oregon and Utah in the United States. Its nat ...
, ''Perognathus longimembris'' *** Merriam's pocket mouse, ''Perognathus merriami'' *** Great Basin pocket mouse, ''Perognathus parvus''


References

* {{Taxonbar, from=Q1232952 Taxa named by Elliott Coues Mammal subfamilies Heteromyidae