Arctic shrew [1] | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Eulipotyphla |
Family: | Soricidae |
Genus: | Sorex |
Species: | S. arcticus |
Binomial name | |
Sorex arcticus Kerr, 1792 | |
Arctic shrew range |
This article needs additional citations for verification .(November 2016) |
The Arctic shrew (Sorex arcticus), also known as the blackback shrew or saddlebacked shrew, is a medium-sized shrew found in Canada and the northern United States. Separate species status has been proposed for the maritime shrew (Sorex maritimensis) which is found in New Brunswick and Nova Scotia and had been considered to be a subspecies of the Arctic shrew. The tundra shrew (Sorex tundrensis) was formerly considered to be a subspecies of the Arctic shrew.
The Arctic shrew is most distinctive in its tricolored fur. It is dark brown or black on its back from its head to the base of its tail, while its flanks are a lighter brown, and its underside is lighter still grayish brown. Even its tail is bi-colored, dark brown on the dorsal side, and gradually fading to a lighter brown on the ventral side. The fur is grayer in winter time, and its tricolor is most marked during the winter months from October to June, for the fur is thicker and brighter. Arctic shrews molt twice a year, and the tricolor bands in the fur are less prominent in younger shrews.
Its body length ranges from 10 to 12 cm (3.9 to 4.7 in) including a 4 cm (1.6 in) long tail. Its mass may range from 5 to 13 g (0.18 to 0.46 oz) and it possesses thirty-two teeth with an average metabolism of 4.7 kilocalories a day.
Arctic shrews are native to North America, ranging from the Arctic Circle in the north and as far south as the northern United States, into North and South Dakota, Wisconsin, Michigan, and Minnesota. Their eastern limits are in eastern Quebec and the Atlantic Maritime provinces, and their western limits are the southern Yukon and Mackenzie valleys. [3]
Arctic shrews are found in a variety of habitats in highest density of 3 to 5 individuals per acre and each individual Arctic shrew appears to limit its range to one tenth of an acre. Of their various habitats, they are found in greatest quantity and density in areas near bodies of water, such as lakes, streams, marshes, wetlands, bogs, swamps, ditches or open areas near wetlands. In the Upper Peninsula of Michigan, they are found densely in spruce and tamarack swamps, in addition to other typical habitats. Arctic shrews have been found in clearings in boreal forests, and occasionally in mixed conifer swamps, dry or old fields, dense grasses near ditches, mixed grasses, in the undergrowth of forest clearings, alder thickets, and dry marsh with grasses, hammock sedges , forbs, cattail, willow, and red-osier shrubs.
There is little information about the mating habits of the Arctic shrew, however males of most shrew species mate with many females, and compete with other males for females, so the assumption is that Arctic shrews behave similarly. In Wisconsin, the breeding season lasts from February to August, and the breeding season is shorter in more northern areas, from April to August. Arctic shrew females give birth to one or two litters each year, and these litters range in size from 4 to 10 offspring, with an average of 7 offspring per litter. The gestation period ranges between 13 and 21 days, so the young stay with their mother until 5 to 6.5 weeks after conception, and males make no contribution to parental care. When they are born, young Arctic shrews are helpless. Their mother cares for them until the end of the weaning period, 20 to 24 days after birth. Both female and male Arctic shrews reach sexual maturity after one year. As much as 50 percent of all juveniles die in the first month, but the average lifespan of an Arctic shrew in the wild is around 18 months.
Arctic shrews are solitary animals. Adults are territorial. In one laboratory study, whenever two Arctic shrews were placed together in a cage, one was dead within several days, though there was no sign of injury to the dead shrew. [4] Arctic shrews are active during day and night, though there are contradicting reports on levels and cycles of activity throughout the day. One claim is that they are least active during mid-morning, while other reports describe alternating periods of activity and rest, with an average of fourteen periods of activity daily. Arctic shrews are very active and move quickly. Periods of inactivity are spent lying on the ground, either on one side or with the ventral side down, body rolled up, and head tucked under the body. Grooming consists of wiping the forefeet rapidly along the mouth. [5]
Like all shrews, the Arctic shrew has a voracious and insatiable appetite due to its quick metabolism. It eats insects, worms and small invertebrates, with a large proportion of its diet made up of larch sawflies, though Arctic shrews in captivity have been fed dead voles, fly pupae, and mealworms. The only known predators of Arctic shrews are great horned owls. [5]
There are two subspecies recognized for this species: [1]
The northern short-tailed shrew is the largest shrew in the genus Blarina, and occurs in the northeastern region of North America. It is a semifossorial, highly active, and voracious insectivore and is present in a variety of habitats like broadleaved and pine forests among shrubs and hedges as well as grassy river banks. It is notable in that it is one of the few venomous mammals. The specific epithet, brevicauda, is a combination of the Latin brevis and cauda, meaning "short tail".
The cinereus shrew or masked shrew is a small shrew found in Alaska, Canada, and the northern United States. This is the most widely distributed shrew in North America, where it is also known as the common shrew.
The American pygmy shrew, also called the eastern pygmy shrew, is a small shrew found throughout much of Alaska, Canada, and the northern contiguous United States, as well as south along the Appalachian Mountains and in a small region in the Colorado and Wyoming Rockies. The species was first discovered in 1831 by naturalist William Cane in Georgian Bay, Parry Sound.
The American water shrew or northern water shrew is a shrew found in the nearctic faunal region located throughout the mountain ranges of the northern United States and in Canada and Alaska. The organism resides in semi-aquatic habitats, and is known for being the smallest mammalian diver.
The marsh shrew, also known as the Pacific water shrew, Bendire's water shrew, Bendire's shrew and Jesus shrew is the largest North American member of the genus Sorex. Primarily covered in dark-brown fur, it is found near aquatic habitats along the Pacific coast from southern British Columbia to northern California. With air trapped in its fur for buoyancy, marsh shrews can run for three to five seconds on top of the water. It measures about 16 cm (6.3 in) in length, including a 7-centimetre (2.8 in)-long tail, and weighs an average of 14.5–16 g (0.51–0.56 oz). The marsh shrew's diet consists mainly of invertebrates, which it hunts on land and in the water. They are rare; their populations are thought to be in decline, and they are considered endangered in parts of their range.
The smoky shrew is a medium-sized North American shrew found in eastern Canada and the northeastern United States and extends further south along the Appalachian Mountains.
The vagrant shrew, also known as the wandering shrew, is a medium-sized North American shrew. At one time, the montane shrew and the Orizaba long-tailed shrew were considered to belong to the same species.
The tundra shrew is a small shrew found in Alaska, the northern Yukon Territory, the MacKenzie Delta region of the Northwest Territories, extreme northwestern British Columbia and eastern Russia. At one time, this animal was considered to be a subspecies of the Arctic shrew.
The Eurasian water shrew, known in the United Kingdom as the water shrew, is a relatively large shrew, up to 10 cm (4 in) long, with a tail up to three-quarters as long again. It has short, dark fur, often with a few white tufts, a white belly, and a few stiff hairs around the feet and tail. It lives close to fresh water, hunting aquatic prey in the water and nearby. Its fur traps bubbles of air in the water which greatly aids its buoyancy, but requires it to anchor itself to remain underwater for more than the briefest of dives.
The common treeshrew is a small mammal in the treeshrew family Tupaiidae, and is native to Thailand, Malaysia, and Indonesia. It has been listed as Least Concern by IUCN as it remains common and displays some adaptability to ongoing habitat loss.
The meadow jumping mouse is the most widely distributed mouse in the family Zapodidae. Its range extends from the Atlantic coast in the east to the Great Plains west, and from the arctic tree lines in Canada and Alaska to the north, and Georgia, Alabama, Arizona, and New Mexico to the south. In mid-2014, the New Mexico subspecies of the meadow jumping mouse, Zapus hudsonius luteus, was listed as an endangered species under the federal Endangered Species Act.
The swamp musk shrew, or musk shrew, is a species of mammal in the family Soricidae. It occurs in Angola, Botswana, Democratic Republic of the Congo, Mozambique, Namibia, South Africa, Eswatini, Zambia and Zimbabwe. Its natural habitat is swamps, and it is a common species in suitable habitats, with the International Union for Conservation of Nature listing it as being of "least concern".
The African giant shrew is a species of white-toothed shrew. It also is known as, Mann's musk shrew, Euchareena's musk shrew, or Olivier's shrew. It is native to Africa, where it has a widespread distribution and occurs in many types of habitat. Its natural habitats are subtropical or tropical dry forest, subtropical or tropical moist lowland forest, subtropical or tropical moist montane forest, dry savanna, moist savanna, arable land, rural gardens, urban areas, and heavily degraded former forest. In the Nile Valley it is found near human habitation, where it is considered to be a pest. It is a common species and is listed by the International Union for Conservation of Nature as being of "least concern".
The Kamchatka shrew is a species of mammal in the family Soricidae. It is endemic to Russia.
The Pribilof Island shrew is a small, short tailed species of mammal in the family Soricidae (shrews). It is endemic to and found only on Alaska's Pribilof Islands. Due to its distinct tricoloured coat, it was originally thought to be related to the Arctic shrew, but it is in fact much closer to the Cinereus shrew in its geographical distribution and morphological traits. Not much is known about the population size, breeding habits, ecology, and the general biology of the shrew.
The ornate shrew is a species of mammal in the family Soricidae (shrews). It is endemic to western North America, ranging from Northern California in the United States to the Baja California peninsula in Mexico. Eight subspecies are known, including the extinct tule shrew, known only from four specimens collected in 1905, and the Suisun ornate shrew, a species of conservation concern in California. Through skull morphology research and genetic testing on Ornate shrew populations, it has been shown that there are three main genetic subdivisions: The Southern, Central and Northern. These three genetic subdivisions of Ornate shrew arose from populations of Ornate shrews getting geographically isolated from other populations.
Preble's shrew is a small shrew distributed across the Great Basin of the United States and southern British Columbia in Canada.
Trowbridge's shrew is a species of mammal in the family Soricidae. It is found in southern British Columbia in Canada and in Washington, Oregon, and California in the United States.
The southeastern shrew is a species of mammal in the family Soricidae. It is found in the southeastern United States.
The long-tailed shrew or rock shrew is a small shrew found in Atlantic Canada and the Northeastern United States.