American pygmy shrew

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American pygmy shrew [1]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Eulipotyphla
Family: Soricidae
Genus: Sorex
Species:
S. hoyi
Binomial name
Sorex hoyi
Baird, 1857 [3]
American Pygmy Shrew area.png
American pygmy shrew range

The American pygmy shrew (Sorex hoyi), also called the eastern pygmy shrew, [4] is a small shrew found throughout much of Alaska, [5] Canada, [6] and the northern contiguous United States, as well as south along the Appalachian Mountains [7] and in a small region in the Colorado and Wyoming Rockies. [8] The species was first discovered in 1831 by naturalist William Cane in Georgian Bay, Parry Sound.[ citation needed ]

Contents

This animal is found in northern coniferous and deciduous forests of North America. It is believed to be the second-smallest mammal in the world, but has an extremely large appetite for its size. Due to its fast metabolism, it needs to eat constantly. It digs through moist soils and decaying leaf litter for food.

Description

The American pygmy shrew is the smallest mammal native to North America and is one of the smallest mammals in the world, just slightly larger than the Etruscan shrew of Eurasia. Its body is about 5 cm (2 in) long including a 2-cm-long tail, and it weighs about 2.0 to 4.5 g (0.07 to 0.16 oz). [9] Its pelage is generally a reddish or grayish brown during the summer, and a white-gray color during the winter. The underside is generally a lighter gray. This animal molts about twice a year, once during late summer, and again during the spring. [10] It has a narrow head with a pointed nose, and whiskers. The eyes are small and well hidden. [11] The primary senses used for hunting are hearing and smell.

Phylogeny

Sorex hoyi was originally placed in the genus Microsorex, which was a subgenus under Sorex until more research had been done. The American pygmy shrew is in the order Soricomorpha and the family Soricidae. [12] Its two closest relatives are the smokey shrew (S. fumeus) and the large-toothed shrew (S. macrodon).[ citation needed ] This genus is believed to have appeared in the late Miocene. [13]

Distribution and habitat

Pygmy shrews are distributed throughout the subalpine and boreal areas of North America, ranging from Canada and Alaska [5] to the Great Lakes and south along the Appalachians. [11] [7] There is also an isolated population in the Colorado and Wyoming Rockies. [8] The species is commonly found in Virginia, Kentucky, North Carolina, South Carolina, Georgia, Tennessee, and Alabama and is the second-most widespread of the long-tailed soricids in the southeast, after the southeastern shrew. [6]

Some pygmy shrew populations comprise their own subspecies. Notably, the geographically isolated pygmy shrews found in the mountain forests of northern Colorado and south-central Wyoming are a unique relictual group from the Pleistocene/Holocene transition, classified as the subspecies S. hoyi montanus. [14] Another subspecies of pygmy shrews is S. hoyi hoyi, which resides in the prairies of eastern South Dakota. [8]

Although S. hoyi prefers moist habitats, it has been recorded to live in areas with both wet and dry soil. However, if it is living in a more arid environment, it needs to have a source of water nearby. [10] Subspecies S. h. montanus occurs in moist coniferous forest, "possibly preferring late-seral stands and the edges between wet and dry forest types." [8] S. h. hoyi has a broader range of habitat but is still mostly found in wet prairies and wetland margins. [8]

Diet

Primarily insectivorous, this animal forages in moist soil and dead leaves to find its prey. Because of the pygmy shrew's small size, its diet primarily consists of insects and insect larvae, while the larger shrews eat insects and worms. [15] Its diet is almost exclusively protein-based. [16] To stay alive, the pygmy shrew has to eat three times its body weight daily, which means capturing prey every 15 to 30 minutes, day and night; a full hour without food means certain death. Because of this high metabolism, the pygmy shrew never sleeps more than a few minutes at a time, as it is in a constant search for food. [9] Although due to its small body size it is always losing body heat, being small has its advantages during the winter when food is scarce. Predators of the American pygmy shrew include hawks, brook trout, owls, snakes, and domestic cats. [17] [7]

Lifecycle and reproduction

Little is known about the reproductive cycle of pygmy shrews. They appear to mate year round, with a bias of births occurring from November through March. [18] The gestation period is estimated to last about 18 days. [11] Females produce a litter of three to eight young, and only give birth once a year. The age the young are weaned is not known with certainty, but by 18 days old, they are nearly full grown, and are usually independent by 25 days. [18] Being mammals, the mother nourishes her young with milk. The maximum lifespan of a pygmy shrew is not known, but it is believed to be about 16–17 months. [18]

Behavior

Pygmy shrews dig through soil and leaf litter to search for food, and can use tunnel networks created by other animals to aid in that search. They do not sleep or rest for extended periods of times, but alternate between rest and activity all day and night, showing a bias towards nighttime. [16] They have keen senses of smell and hearing to help them find prey. [11] When feeling threatened or scared, the shrews make a sharp squeaking noise and run for cover. Shrews can also swim, which makes them prey to brook trout. Pygmy shrews are in constant motion, and captured shrews have been observed "climbing and walking upside down on the wire top of the cage." [10]

Physiology

Due to its high metabolism, the pygmy shrew is active year-round and does not engage in any form of torpor or hibernation. Shrews have been known to burrow through snow to find food, showing that winter snow does not stop them. Though pygmy shrews are constantly losing body heat due to their small size, their small size also has benefits, as they require less food to generate sufficient energy than would a larger shrew. [15]

Although usually a positive correlation exists between latitude and shrew body size, the American pygmy shrew is an exception. [15]

Related Research Articles

<span class="mw-page-title-main">Shrew</span> Family of mammals

Shrews are small mole-like mammals classified in the order Eulipotyphla. True shrews are not to be confused with treeshrews, otter shrews, elephant shrews, West Indies shrews, or marsupial shrews, which belong to different families or orders.

<span class="mw-page-title-main">Etruscan shrew</span> Species of mammal

The Etruscan shrew, also known as the Etruscan pygmy shrew, white-toothed pygmy shrew and Savi's pygmy shrew, is the smallest known extant mammal by mass, weighing only about 1.8 g (0.063 oz) on average.

<span class="mw-page-title-main">Northern short-tailed shrew</span> Species of mammal

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".

<span class="mw-page-title-main">Cinereus shrew</span> Species of mammal

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.

<span class="mw-page-title-main">Arctic shrew</span> Species of mammal

The Arctic shrew, 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 which is found in New Brunswick and Nova Scotia and had been considered to be a subspecies of the Arctic shrew. The tundra shrew was formerly considered to be a subspecies of the Arctic shrew.

<span class="mw-page-title-main">American water shrew</span> Species of mammal

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.

<span class="mw-page-title-main">North American least shrew</span> Species of mammal

The North American least shrew is one of the smallest mammals, growing to be only up to 3 inches long. It has a long pointed snout and a tail never more than twice the length of its hind foot. The dense fur coat is either grayish-brown or reddish-brown with a white belly. Its fur becomes lighter in the summer and darker in the winter. Although similar in appearance to several species of rodents, all shrews are members of the order Eulipotyphla and should not be mistaken for a member of the order Rodentia. The North American least shrew's eyes are small and its ears are completely concealed within its short fur, giving it very poor eyesight and hearing.

<span class="mw-page-title-main">Smoky shrew</span> Species of mammal

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.

<span class="mw-page-title-main">Vagrant shrew</span> Species of mammal

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.

<i>Sorex</i> Genus of mammals

The genus Sorex includes many of the common shrews of Eurasia and North America, and contains at least 142 known species and subspecies. Members of this genus, known as long-tailed shrews, are the only members of the tribe Soricini of the subfamily Soricinae. They have 32 teeth.

<span class="mw-page-title-main">American shrew mole</span> Species of mammal

The American shrew mole is the smallest species of mole. It is the only living member of the genus Neurotrichus and the tribe Neurotrichini. It is also known as Gibb's shrew mole and least shrew mole. It is not closely related to the Asian shrew mole. The reason that it is called a "shrew mole" instead of being called either a "shrew" or a "mole" is because of its fur, which is a characteristic of shrews and its large head and heavy dentition, which is characteristic of moles.

<span class="mw-page-title-main">Eurasian pygmy shrew</span> Species of mammal

The Eurasian pygmy shrew, often known simply as the pygmy shrew, is a widespread shrew of the northern Palearctic.

<span class="mw-page-title-main">Common shrew</span> Species of mammal

The common shrew, also known as the Eurasian shrew, is the most common shrew, and one of the most common mammals, throughout Northern Europe, including Great Britain, but excluding Ireland. It is 55 to 82 millimetres long and weighs 5 to 12 grams, and has velvety dark brown fur with a pale underside. It is one of the rare venomous mammals. Juvenile shrews have lighter fur until their first moult. The common shrew has small eyes, a pointed, mobile snout and red-tipped teeth. It has a life span of approximately 14 months.

<span class="mw-page-title-main">Eurasian least shrew</span> Species of mammal

The Eurasian least shrew, also called the lesser pygmy shrew, is the second-smallest mammal by mass after the Etruscan shrew.

<span class="mw-page-title-main">African giant shrew</span> Species of mammal

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".

<span class="mw-page-title-main">Montane shrew</span> Species of mammal

The montane shrew is a species of mammal in the family Soricidae commonly known as the dusky shrew. Monticolus is derived from the Latin root word mons meaning mountain. It is found in Alaska, western Canada, the western United States in Washington, Idaho, Montana, Utah, Colorado, New Mexico, Arizona, Oregon, Nevada, and California, as well as in Mexico.

<span class="mw-page-title-main">Ornate shrew</span> Species of mammal

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.

<span class="mw-page-title-main">Shinto shrew</span> Species of mammal

The Shinto shrew is a species of shrew of the genus Sorex that lives only on the islands of Japan. It is a mole-like mammal with a pointed snout, very small ears, and a relatively long tail. Like most shrews, it is tiny, has poor eyesight, and a very good sense of hearing and smell which it uses to locate its prey, mainly insects.

<span class="mw-page-title-main">Southeastern shrew</span> Species of mammal

The southeastern shrew is a species of mammal in the family Soricidae. It is found in the southeastern United States.

<span class="mw-page-title-main">Long-tailed shrew</span> Species of mammal

The long-tailed shrew or rock shrew is a small shrew found in Atlantic Canada and the Northeastern United States.

References

  1. ↑ Hutterer, R. (2005). Wilson, D.E.; Reeder, D.M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 289. ISBN   978-0-8018-8221-0. OCLC   62265494.
  2. ↑ Cassola, F. (2017) [errata version of 2016 assessment]. "Sorex hoyi". IUCN Red List of Threatened Species . 2016: e.T41400A115183871. doi: 10.2305/IUCN.UK.2016-3.RLTS.T41400A22312472.en . Retrieved 8 November 2022.
  3. ↑ Baird, Spencer F. (1857). "Mammals". Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean. Vol. 8. Washington: Beverly Tucker. pp. 32–33.
  4. ↑ "Sorex hoyi - Eastern Pygmy Shrew". explorer.natureserve.org. NatureServe. 2024-07-05. Archived from the original on 2024-07-11. Retrieved 2024-07-09.
  5. 1 2 Jung, Thomas S.; Pretzlaw, Troy D.; Nagorsen, David W. (2007). "Northern range extension of the pygmy shrew, Sorex hoyi, in the Yukon". The Canadian Field-Naturalist. 121: 94. doi: 10.22621/cfn.v121i1.402 . Retrieved 2015-11-19.
  6. 1 2 Ford, W. Mark; Laerm, Joshua; Chapman, Brian R. Pygmy Shrew (PDF) (Report). U.S. Forest Service . Retrieved 2024-07-30.
  7. 1 2 3 Saunders, D. A. (1988). "Pygmy Shrew". Adirondack Mammals. New York: State University of New York, College of Environmental Science and Forestry. Archived from the original on 2024-07-20. Retrieved 2024-07-30.
  8. 1 2 3 4 5 Beauvais, Gary P.; McCumber, Jacob (2006-11-30). Pygmy Shrew (Sorex hoyi): a technical conservation assessment (PDF) (Report). U.S. Forest Service. p. 3. Archived (PDF) from the original on 2023-06-28.
  9. 1 2 "Pygmy Shrew: America's Smallest Mammal—and Its Hungriest". www.nwf.org. Retrieved 2018-09-06.
  10. 1 2 3 "Index for Mammalian Species". www.science.smith.edu. Archived from the original on 2012-11-24. Retrieved 2015-11-16.
  11. 1 2 3 4 "Sorex hoyi (pygmy shrew)". Animal Diversity Web. Retrieved 2015-11-16.
  12. ↑ "NatureServe Explorer 2.0". explorer.natureserve.org. Retrieved 2024-02-18.
  13. ↑ Wolsan, Mieczysław; Wójcik, Jan Marek, eds. (1998). Evolution of shrews. Białowieża: Mammal Research Institute. Polish Academy of Sciences. ISBN   978-83-907521-0-5.
  14. ↑ Beauvais & McCumber 2006, pp. 3, 23.
  15. 1 2 3 Churchfield, Sara (2002-03-01). "Why are shrews so small? The costs and benefits of small size in northern temperateSorex species in the context of foraging habits and prey supply". Acta Theriologica. 47 (1): 169–184. doi:10.1007/BF03192486. ISSN   0001-7051. S2CID   7593435.
  16. 1 2 Buckner, Charles H. (1964-03-01). "Metabolism, Food Capacity, and Feeding Behavior in Four Species of Shrews". Canadian Journal of Zoology. 42 (2): 259–279. doi:10.1139/z64-026. ISSN   0008-4301.
  17. ↑ Wund, Matthew. "Sorex hoyi (pygmy shrew)". Animal Diversity Web. Retrieved 2024-02-18.
  18. 1 2 3 Feldhamer, George A.; Klann, Ronald S.; Gerard, Anthony S.; Driskell, Amy C. (1993-05-21). "Habitat Partitioning, Body Size, and Timing of Parturition in Pygmy Shrews and Associated Soricids". Journal of Mammalogy. 74 (2): 403–411. doi:10.2307/1382396. ISSN   0022-2372. JSTOR   1382396.
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