Allen's chipmunk (''Neotamias senex'') is a species of

chipmunk Chipmunks are small, striped rodents of the family Sciuridae. Chipmunks are found in North America, with the exception of the Siberian chipmunk which is found primarily in Asia. Taxonomy and systematics Chipmunks may be classified either as ...

. It is also known as the shadow chipmunk. It is native to the western United States, where it occurs in

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...

, and

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

. It is a common species of the

Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primar ...

. ''Neotamias senex's'' length measures about 229-261 mm. Female chipmunks are larger compared to males, with a dimorphism ratio of 1.033. Females weigh around 73.0 grams to 108.5 grams, while males weigh 66.8 grams to 99.3 grams. This chipmunk generally prefers mature coniferous forests and

chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranea ...

slopes dominated by

ponderosa pine ''Pinus ponderosa'', commonly known as the ponderosa pine, bull pine, blackjack pine, western yellow-pine, or filipinus pine is a very large pine tree species of variable habitat native to mountainous regions of western North America. It is the ...

Jeffrey pine ''Pinus jeffreyi'', also known as Jeffrey pine, Jeffrey's pine, yellow pine and black pine, is a North American pine tree. It is mainly found in California, but also in the westernmost part of Nevada, southwestern Oregon, and northern Baja Califo ...

sugar pine ''Pinus lambertiana'' (commonly known as the sugar pine or sugar cone pine) is the tallest and most massive pine tree, and has the longest cones of any conifer. The species name ''lambertiana'' was given by the Scottish botanist David Douglas, ...

, black oak,

Douglas fir The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Oregon pine, and Columbian pine. There are three v ...

white fir ''Abies concolor'', the white fir, is a coniferous tree in the pine family Pinaceae. This tree is native to the mountains of western North America, including the Cascade Range and southern Rocky Mountains, and into the isolated mountain ranges ...

, red fir, incense cedar, and

mountain hemlock ''Tsuga mertensiana'', known as mountain hemlock, is a species of hemlock native to the west coast of North America, found between Southcentral Alaska and south-central California. Description ''Tsuga mertensiana'' is a large evergreen conifer ...

. The shrub layer includes buckbrush,

manzanita Manzanita is a common name for many species of the genus ''Arctostaphylos''. They are evergreen shrubs or small trees present in the chaparral biome of western North America, where they occur from Southern British Columbia and Washington to Or ...

blackberry The blackberry is an edible fruit produced by many species in the genus ''Rubus'' in the family Rosaceae, hybrids among these species within the subgenus ''Rubus'', and hybrids between the subgenera ''Rubus'' and ''Idaeobatus''. The taxonomy ...

, and chinquapin. A study in the Sierra Nevada found that Allen's chipmunk was more abundant in red fir than in mixed conifer woodland. Like other chipmunks, Allen's chipmunk is omnivorous. Their diet consists largely of vegetation: mushrooms, berries, nuts, shoots, seeds and grains. But chipmunks also eat other animals, including insects, frogs, bird eggs and occasionally baby birds. They are in turn prey for minks, weasels, and owls. Allen's chipmunk is active all year round except during stretches of harsh winter weather.

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Further reading