Chipmunks are small, stripedsquirrels of subtribeTamiina. Chipmunks are found inNorth America, with the exception of theSiberian chipmunk, which is found primarily inAsia. The name "chipmunk" originated in the 19th century, and other names for this group of squirrels include chitmunk, chipmuck, chipping squirrel, andground squirrel, though the last name can refer to squirrels of othergenera.
Chipmunks areomnivorous animals, and have diets that primarily include seeds, nuts, fruits and buds but may extend to include other plant matter,fungi, insects, small frogs, worms, bird eggs andnestlings. Their varied diet allows them to feed on plants such as grains and vegetables grown by humans, which has led them to be consideredpests in some areas. Many species of chipmunk will commonly carry food items in theircheek pouches back to theirburrows to eat or store for winter, and this seed storing behavior contributes to thedispersal and establishment ofseedlings and fungi in forests.
Taxonomy and systematics
Chipmunks are classified as four genera:Tamias, of which theeastern chipmunk (T. striatus) is the only living member;Eutamias, of which theSiberian chipmunk (E. sibiricus) is the only living member;Nototamias, which consists of three extinct species, andNeotamias, which includes the 23 remaining, mostly western North American, species. These classifications were treated as subgenera due to the chipmunks' morphological similarities.[1] As a result, most taxonomies over the twentieth century have placed the chipmunks into a single genus.[2] Joseph C. Moore reclassified chipmunks to form the subtribe Tamiina within the tribeMarmotini in a 1959 study,[3] and this classification of three living genera of chipmunks rather than a single chipmunk genus has been supported by studies ofmitochondrial DNA performed from 2000 to 2010.[4]
The common name originally may have been spelled "chitmunk", from the nativeOdawa (Ottawa) wordjidmoonh, meaning "red squirrel" (cf.Ojibweᐊᒋᑕᒨajidamoo).[5][6] The earliest form cited in theOxford English Dictionary is "chipmonk", from 1842. Other early forms include "chipmuck" and "chipminck", and in the 1830s they were also referred to as "chip squirrels", probably in reference to the sound they make. In the mid-19th century,John James Audubon and his sons included a lithograph of the chipmunk in theirViviparous Quadrupeds of North America, calling it the "chipping squirrel [or] hackee".[7] Chipmunks have also been referred to asground squirrels[8] (although the name "ground squirrel" may refer to other squirrels, such as those of the genusSpermophilus).[9]
Diet
An eastern chipmunk placing food in its cheek pouch
Chipmunks have anomnivorous diet primarily consisting of seeds,nuts and other fruits, andbuds.[10][11] They also commonly eat grass, shoots, and many other forms of plant matter, as well asfungi, insects and otherarthropods, small frogs, worms, and bird eggs. They will also occasionally eat newly hatched baby birds.[10][11][12] Around humans, chipmunks can eat cultivated grains and vegetables, and other plants from farms and gardens, so they are sometimes considered pests.[10][13] Chipmunks mostly forage on the ground, but they climb trees to obtain nuts such ashazelnuts andacorns.[10][14] At the beginning of autumn, many species of chipmunk begin tostockpile nonperishable foods for winter. They mostly cache their foods in a larder in their burrows and remain in their nests until spring, unlike some other species which make multiple small caches of food.[10]Cheek pouches allow chipmunks to carry food items to their burrows for either storage or consumption.[11]
Ecology and life history
Chipmunks in northernWisconsinEastern chipmunk at the entrance of its burrow
Eastern chipmunks, the largest of the chipmunks,[15] mate in early spring and again in early summer, producing litters of four or five young twice each year.[10] Western chipmunks breed only once a year. The young emerge from the burrow after about six weeks and strike out on their own within the next two weeks.[16]
These small mammals fulfill several important functions inforestecosystems. Their activities harvesting and hoarding tree seeds play a crucial role inseedling establishment. They consume many different kinds offungi, including those involved insymbiotic mycorrhizal associations with trees, and are avector for dispersal of the spores of subterraneansporocarps (truffles) in some regions.[17] Movement or storage of seeds in soil caused by chipmunks leads to the germination of new plants.[18]
Chipmunks construct extensiveburrows which can be more than 3.5 m (11 ft) in length with several well-concealed entrances.[19] The burrows are complex and include plugged entryways,[20] separate compartments for nesting, multiple food chambers, side pockets and escape routes.[21] The sleeping quarters are kept clear of shells, and feces are stored in refuse tunnels.[22] They arediurnal.[23] though The eastern chipmunkhibernates in the winter, while western chipmunks do not, relying on the stores in their burrows.[24] Chipmunks play an important role as prey for various predatory mammals and birds, but are also opportunistic predators themselves. This is particularly the case with regard to bird eggs andnestlings, as in the case ofeastern chipmunks andmountain bluebirds.[25]
Chipmunks typically live about three years, although some have been observed living to nine years in captivity.[26] In captivity, they are said to sleep for an average of about 15 hours a day. It is thought that mammals which can sleep in hiding, such as rodents and bats, tend to sleep longer than those that must remain on alert.[23]
^Nichols, John D. and Earl Nyholm (1995).A Concise Dictionary of Minnesota Ojibwe. Minneapolis: University of Minnesota Press.
^Audubon, John James; Bachman, John (1967).Imperial Collection of Audubon Mammals. New York: Bonanza Books, a division ofCrown Publishing Group. p. 52.
^Kryštufek, B.; B. Vohralík (2013). "Taxonomic revision of the Palaearctic rodents (Rodentia). Part 2. Sciuridae: Urocitellus, Marmota and Sciurotamias".Lynx, N. S. (Praha).44: 22.
^abJennifer S. Holland "40 Winks?" (July 2011).National Geographic Vol. 220, No. 1.
^Kays, R. W.; Wilson, Don E. (2009).Mammals of North America (2nd ed.). Princeton University Press. p. 72.ISBN978-0-691-14092-6.
^Sullivan, Janet."WILDLIFE SPECIES: Sialia currucoides".Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved23 January 2016.
Gordon, Kenneth Llewellyn (1943).The Natural History and Behavior of the Western Chipmunk and the Mantled Ground Squirrel. Oregon State College Monographs. Studies in zoology, no. 5. Corvallis, Or.: Oregon State College.LCCN44053700.OCLC752445896.
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