American ermine

The American ermine has a body plan typical of weasels. It has short legs, a long body and neck, and a small triangular head with short round ears. It has a brown dorsum with a white venter (except during winter when the coat is fully white) and a short, black-tipped tail.{{Cite book |last=Frey |first=Jennifer K. |title=Wild Carnivores of New Mexico |date=2023 |publisher=University of New Mexico Press |isbn=9780826351531 |pages=667 |language=English}}

It was long considered conspecific with the stoat (M. erminea), but a 2021 study found it to be a distinct species, forming distinct genetic clades from erminea.{{Cite journal|last1=Colella|first1=Jocelyn P.|last2=Frederick|first2=Lindsey M.|last3=Talbot|first3=Sandra L.|last4=Cook|first4=Joseph A.|date=2021|title=Extrinsically reinforced hybrid speciation within Holarctic ermine (Mustela spp.) produces an insular endemic|journal=Diversity and Distributions|language=en|volume=27|issue=4|pages=747–762|doi=10.1111/ddi.13234|issn=1472-4642|doi-access=free|bibcode=2021DivDi..27..747C }}{{Cite web|title=Distinct Species of Adorable Weasels Have Been Hiding in Plain Sight|url=https://gizmodo.com/distinct-species-of-adorable-weasels-have-been-hiding-i-1846673520|access-date=2021-07-12|website=Gizmodo|date=13 April 2021 |language=en-us}}{{Cite web|title=Adorable Killer Ermines Found To Contain Three Distinct Species Of Fluffy Weasels|url=https://www.iflscience.com/plants-and-animals/adorable-killer-ermines-found-to-contain-three-distinct-species-of-fluffy-weasels/|access-date=2021-07-12|website=IFLScience|date=15 April 2021 |language=en}} The finding has been accepted by the American Society of Mammalogists.{{Cite web|title=Mustela richardsonii Bonaparte, 1838|url=https://www.mammaldiversity.org/explore.html#genus=Mustela&species=richardsonii&id=1006533|access-date=2021-07-12|website=www.mammaldiversity.org}} The Haida ermine (M. haidarum) is thought to be a hybrid species originating from ancient hybridization between M. erminea and M. richardsonii.

The species is found throughout most of North America aside from most of Alaska (although it is found on some islands in southeastern Alaska), eastern Yukon, most of Arctic Canada, and Greenland, where it is replaced by M. erminea. It reaches the northern extent of its range in Ellesmere Island and a portion of eastern mainland Nunavut and ranges from here to cover almost all of western North America south to northern New Mexico, and eastern North America south to northern Virginia. It is absent from most of the Southeastern United States and the Great Plains.

In North America, where the ecological niche for rat- and rabbit-sized prey is taken by the larger long-tailed weasel (Neogale frenata), the American ermine preys on mice, voles, shrews, young cottontails,{{Harvnb|Verts|Carraway|1998|p=417}} chipmunks, deer mice, jumping mice, and house mice. Usually the ermine kills by biting at base of skull. Small birds, frogs, small fish, and earthworms are other types of prey for ermines.Ahlborn, G. “Life History Account for Ermine.” Life History Accounts for Species in the California Wildlife Habitat Relationships (CWHR) System, 1988.

Ermines live and find cover from predators in hollow spaces from logs, burrows and man made structures. Ermines sometimes den within their prey's nest and use their skin and fur as a lining for their den.

They breed in dense parts of the forest. The season for breeding is late springtime to the summer from July to August. The males mature in a year while the females only take three to four weeks to mature. The females carry a litter of four to seven babies for 255 days then gives birth.

Some of the larger wild predators of ermines are minks, martens, fishers, bobcats, coyotes, and large owls and hawks. Occasionally a domesticated cat or dog may kill an ermine. Their small agile bodies help them evade these predators, while also allowing them to compete with their predators for food in more barren months.

About 13 subspecies are known:

The fur of ermine was valued by the Tlingit and other indigenous peoples of the Pacific Northwest Coast. They could be attached to traditional regalia and cedar bark hats as status symbols or made into shirts.{{cite web|title=Tlingit Ermine-Skin Shirt (Daa dugu k'oodas')|url=http://www.corbisimages.com/stock-photo/rights-managed/IH011277/tlingit-ermineskin-shirt-daa-dugu-koodas}}

File:Stoat and chipmunks.png|American ermine surplus killing a family of chipmunks, as illustrated by Ernest Thompson Seton

File:Frenataermineanivalis.png|Skulls of a long-tailed weasel (top), an American ermine (bottom left), and least weasel (bottom right), as illustrated in Merriam's Synopsis of the Weasels of North America

File:American Ermine, FWG.jpg|Winter coat

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• {{Cite book|last=Merriam|first=Clinton Hart|url=https://archive.org/details/synopsisofweasel00merriala|title=Synopsis of the weasels of North America |location=Washington, D.C. |publisher=Govt. Print. Off.|year=1896}}
• {{Cite book|last1=Verts|first1=B. J.|last2=Carraway|first2=Leslie N.|url=https://books.google.com/books?id=8KI1AmzIDnwC&pg=PA415 |title=Land Mammals of Oregon|publisher=University of California Press|year=1998|isbn=0-520-21199-5}}

{{Weasels}}

{{Carnivora|M.}}

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Category:Weasels

Category:Mammals of Canada

Category:Mammals of North America

Category:Taxa named by Charles Lucien Bonaparte

Category:Mammals described in 1838

Category:Taxobox binomials not recognized by IUCN