Little chipmunk
| Little chipmunk | ||||||||||||
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Little chipmunk ( Tamias minimus ) |
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| Tamias minimus | ||||||||||||
| Bachman , 1839 |
The little chipmunk ( Tamias minimus , Syn . : Neotamias minimus ) is a type of squirrel from the genus of the chipmunk ( Tamias ). It occurs in numerous subspecies in large parts of North America in central to southern Canada and in the United States , making it by far the most widespread species of the genus in North America.
features
The little chipmunk reaches an average head-torso length of about 10.6 to 11.4 centimeters, the tail length is about 8.0 to 8.5 centimeters and the weight is about 45 to 50 grams. It is a very small chipmunk. Within the very large distribution area, the species occurs in numerous subspecies, some of which differ very clearly in appearance. The back color is generally red to cinnamon brown or gray. As with other species of the genus, there are several dark back stripes on the back, separated by lighter stripes and delimited from the sides of the body. The species also has characteristic light stripes on the face, between which a dark stripe runs over the eyes. Often there is a light spot behind the ears, a postauricular spot. The belly is white to creamy white, sometimes gray to grayish white. The underside of the tail varies from reddish brown to yellowish to brown.
From the numerous other small chipmunks with which the small chipmunk lives in parts of the distribution area, it can often only be distinguished by features of the skull or details of the coloration.
distribution
The little chipmunk is found in large parts of North America in central to southern Canada and in the United States . The distribution ranges from the Yukon River in northeast Canada to the west of Québec and Michigan and from there south to New Mexico , Arizona and the Sierra Nevada in California .
Way of life
Small chipmunks live in numerous, very different habitats in their range. They prefer open forest areas with little undergrowth and near water, especially in the Green River system in Utah, Wyoming, and Colorado. In many regions the choice of habitat is dependent on competition from other chipmunks; For example, the little chipmunk in western Colorado is often tied to trees, but when the Hopi chipmunk ( Tamias rufus ) is present, it switches to bushes.
The species is diurnal with main activities in the early morning and late afternoon. It lives primarily on the ground, but can also climb trees and bushes. The animals feed mainly herbivorous of seeds, the regional availability plays a major role. In addition, other parts of the plant such as leaves and fruits as well as insects and small vertebrates are used as supplementary food. The animals build underground burrows for wintering and as nests, but there are also nests made of leaves in the branches or they colonize tree hollows. The earthworks are very shallow with a maximum depth of 0.5 to 1 meter and short corridors of 0.4 to 3.5 meters in length. They consist of one or two chambers and have one to three exits. The territory of the animals varies in size from region to region. In research in Alberta, Canada, the average male territory was found to be 1.22 hectares and that of the males 0.66 hectares . Trap data in other regions suggest smaller territories. The animals communicate through various calls and whistles and five or six different alarm calls are documented, but not examined in more detail.
The mating season depends on the region and the climatic conditions. It begins shortly after the females have finished wintering; the females ovulate after about seven days. The gestation period is 28 to 30 days. Depending on the region, the litter consists of an average of 4 to 6.5 young animals, as a rule the animals only have one litter per year. lactating females have been documented from May to late August.
In the largest part of the distribution area the species occurs sympatric with other chipmunks. In competition with other species of chipmunks and other ground squirrels, the little chipmunk often retreats, but is able to use different habitats efficiently due to its great adaptability. In the Rocky Mountains , for example, the little chipmunk occurs together with the yellow spruce chipmunk ( Tamias amoenus ) and usually colonizes the higher regions. With experimental regional distances of the yellow spruce chipmunk, their habitats were quickly colonized by the little chipmunk, the former can accordingly be viewed as more competitive in these habitats, but cannot colonize the extended habitats of the little chipmunk. As small mammals, the animals are likely to be preyed on by various predators such as martens, cats and dogs as well as birds of prey, but no predators have been specifically proven and the little chipmunk probably benefits from its small size and mobility. Several species of animal lice , fleas , mites and ticks, as well as a bot fly , have been identified as ectoparasites . As a carrier of various viruses and bacteria, the little chipmunk can also be relevant for the transmission of pathogens that are potentially relevant to humans. The species is the carrier and pathogen reservoir of the Colorado tick fever and possibly also the bacterium Borrelia burgdorferi , the causative agent of Lyme borreliosis . The species is also susceptible to the plague pathogen Yersinia pestis and Bartonella .
Systematics
The little chipmunk is classified as an independent species within the genus of chipmunks ( Tamias ), which consists of 25 species. The first scientific description comes from the American priest and naturalist John Bachman from 1839, who described it using individuals from the Colorado River near Green River in Sweetwater County , Wyoming. Within the chipmunk group, the little chipmunk, along with most of the other species, is assigned to the subgenus Neotamias , which is also discussed as an independent genus. In some cases, different species that are independent today were regarded as subspecies.
Within the species, 21 subspecies are distinguished together with the nominate form :
- Tamias minimus minimus : nominate form; the form occurs on the plains and intermediate altitudes in Wyoming , northeastern Utah, and northwestern Colorado . The basic color is matt gray to grayish and sand-colored mottled. The hair on the underside of the tail is red-brown with black banding and sand-colored delimitation.
- Tamias minimus arizonensis : from the Prieto Plateau at the southern end of the Blue Range in Greenlee County , Arizona. The color of the subspecies corresponds to Tamias minimus consobrinus , but is grayer and less sand-colored. The shoulders are washed in pale smoky gray, the tail is light sand-colored on the underside.
- Tamias minimus atristriatus : from Piñasco in New Mexico. The sides of the body are gray reddish brown, the underside is yellowish white. The light stripes on the back are gray to white in color with a rust-red or sand-colored tinge. Compared to the similar Tamias minimus operarius , the subspecies is somewhat larger, darker and more dull in color.
- Tamias minimus borealis : in Canada and in the higher areas of Montana. The autumn color of the animals is pale yellowish gray, the sides of the body are washed with a yellowish brown. The ventral side is garu-white with a sand-colored impact. The dark back stripes are black, the light gray stripes and the outermost stripes white with a yellowish tinge.
- Tamias minimus cacodemus : described from the "Sheep Mountains, Big Bad Lands", referring to the White River Badlands in South Dakota . The subspecies corresponds to Tamias minimus pallidus , but is about paler with a very long tail.
- Tamias minimus caniceps : in Canada from the Yukon River to British Columbia . The subspecies corresponds to Tamias minimus borealis , but is grayer mainly on the head, feet and tail and the underside is white.
- Tamias minimus caryi : In the San Luis Valley in Colorado. The shape corresponds to the nominate shape, but is somewhat paler and grayer. The facial stripes are white.
- Tamias minimus chuskaensis : in the Chuska Mountains in Arizona and New Mexico. Compared to the nominate form, this subspecies is paler. The top of the feet is gray, the underside of the tail yellowish to reddish brown, delimited by a pale sand-colored area.
- Tamias minimus confinis : in the Brighthorn Mountains in northern Wyoming. The subspecies corresponds to Tamias minimus consobrinus , but is somewhat larger and the basic color in the winter coat is more sand-colored. The dark back stripes are black with ocher-dark brown parts.
- Tamias minimus consobrinus : in Utah and Colorado along the northern border areas with Idaho and Wyoming. The underside of the tail is reddish brown.
- Tamias minimus grisescens : in central Washington . The subspecies is similar to Tamias minimus pictus , but is grayer, less sand-colored and smaller. The dark stripes on the back are narrower and the tail is paler and grayer.
- Tamias minimus hudsonius : in northern Manitoba in Canada. The shape is similar to Tamias minimus borealis , but is darker gray in color. The underside of the tail is paler and there is less red on the shoulders, back and torso. The hind legs are dark gray, the dark back stripes are wider.
- Tamias minimus jacksoni : in Oneida County in Wisconsin . The subspecies is similar to Tamias minimus borealis , but the top and tail are more yellow-brown and the face and head and tail are generally darker.
- Tamias minimus neglectus : in southern Manitoba and Ontario in Canada and in northern Minnesota and Wisconsin. The shape resembles Tamias minimus borealis , but is larger and more vividly colored.
- Tamias minimus operarius : in western Colorado to northern New Mexico, eastern Utah and southern Wyoming. The subspecies is similar to the yellow spruce chipmunk ( Tamias amoenus ), but in contrast to this, it does not have a black color on the ear. The tail is longer, the top of the tail is reddish brown.
- Tamias minimus oreocetes : from the southern border between Alberta and British Columbia in Canada to Montana in the United States. The basic color is grayish, with yellowish washings on the sides of the body, the head is mottled gray on the upper side. The outermost light back stripes are white. The underside of the tail is pale red-brown and black bordered. The top of the tail is greyish yellow.
- Tamias minimus pallidus : from Montana, east North Dakota and northeast Wyoming to South Dakota and Nebraska . The subspecies corresponds to the nominate form, but is larger and the sides of the body are more ocher in color.
- Tamias minimus pictus : in southern Idaho and northern Utah. Compared to the nominate form, the upper side is paler. The basic color is slate gray, the sides of the body are pale yellow-sand colored. The middle dark back stripes are black, the outer brown with red-brown delimitation. The outer pair of light stripes is white, the middle light stripes slate gray. The top of the tail is black and yellowish-gray, the underside is dark yellowish sand-colored with black delimitation and yellowish-gray coloring.
- Tamias minimus scrutator : from central to southern Washington, central Oregon and southwestern Idaho south to California's Sierra Nevada and west to Nevada. Compared to the nominate form, this subspecies is smaller and has cinnamon-colored body sides. It corresponds to Tamias minimus consobrinus , but is lighter and less reddish-brown. Compared to Tamias minimus pictus , it has a shorter tail and the top of the head is darker.
- Tamias minimus selkirki : only detected at the Paradise Mine near Toby Creek west of Invermere in British Columbia, Canada. The outer dark stripes are brown, the inner black. The inner light stripes are strongly discolored gray and brown. The spot behind the ears (postauricular spot) is gray-white, the sides of the body are cinnamon-colored. The underside of the tail is colored pink-cinnamon to cinnamon-sand.
- Tamias minimus silvaticus : in the border region between Wyoming and South Dakota. The subspecies is large and the body color is gray-brown. The sides of the body are ocher-sand-colored. The underside of the tail is ocher-orange with a black border. Compared to Tamias minimus pallidus , the underside is darker and redder, and the stripes of the head are darker.
Status, threat and protection
The little chipmunk is classified by the International Union for Conservation of Nature and Natural Resources (IUCN) as "Least Concern" (LC). This is justified by the very large distribution area and the regular occurrence, there are no known risks to the existence of the plant. The species occurs frequently to very frequently in the range and is very adaptable, large parts of the range and habitats are in protected areas.
The subspecies Tamias minimus atristriatus in New Mexico is considered critically endangered, Tamias minimus selkirki is considered endangered.
supporting documents
- ↑ a b c d e f g h i j k l Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012, ISBN 978-1-4214-0469-1 , pp. 325-327 .
- ↑ a b c Neotamias minimus in the IUCN Red List of Threatened Species 2015.4. Submitted by: AV Linzey, NatureServe (G. Hammerson), 2008. Retrieved June 26, 2016.
- ↑ a b Tamias (Neotamias) minimus In: Don E. Wilson , DeeAnn M. Reeder (Ed.): Mammal Species of the World. A taxonomic and geographic Reference. 2 volumes. 3. Edition. Johns Hopkins University Press, Baltimore MD 2005, ISBN 0-8018-8221-4 .
- ^ BJ Verts, Lesley N. Carraway: Tamias minimus. ( Memento of the original from June 6, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Mammalian Species 653, 2001.
- ↑ Bruce D. Patterson, Ryan W. Norris: Towards a uniform nomenclature for ground squirrels: the status of the Holarctic chipmunks. Mammalia 80 (3), May 2016; Pp. 241-251 doi : 10.1515 / mammalia-2015-0004
literature
- Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012, ISBN 978-1-4214-0469-1 , pp. 325-327 .
- BJ Verts, Lesley N. Carraway: Tamias minimus. Mammalian Species 653, 2001.
Web links
- Neotamias minimus inthe IUCN Red List of Threatened Species 2015.4. Submitted by: AV Linzey, NatureServe (G. Hammerson), 2008. Retrieved June 26, 2016.