| American ermine | |
|---|---|
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| NearBeaverhill Lake,Alberta | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Family: | Mustelidae |
| Genus: | Mustela |
| Species: | M. richardsonii |
| Binomial name | |
| Mustela richardsonii Bonaparte, 1838 | |
| Subspecies | |
See text | |
| Synonyms | |
| |
TheAmerican ermine orAmerican stoat (Mustela richardsonii) is a species ofmustelid native to most ofNorth America. Thespecific epithet refers to Arctic explorer and naturalistJohn Richardson.
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.[2]
It was long considered conspecific with thestoat (M. erminea), but a 2021 study found it to be a distinct species, forming distinct genetic clades fromerminea.[3][4][5] The finding has been accepted by theAmerican Society of Mammalogists.[6] TheHaida ermine (M. haidarum) is thought to be ahybrid species originating from ancienthybridization betweenM. erminea andM. richardsonii.[3]
The species is found throughout most of North America aside from most ofAlaska (although it is found on some islands insoutheastern Alaska), easternYukon, most ofArcticCanada, andGreenland, where it is replaced byM. erminea. It reaches the northern extent of its range inEllesmere Island and a portion of eastern mainlandNunavut and ranges from here to cover almost all ofwestern North America south to northernNew Mexico, andeastern North America south to northernVirginia. It is absent from most of theSoutheastern United States and theGreat Plains.[3]
In North America, where theecological niche for rat- and rabbit-sized prey is taken by the largerlong-tailed weasel (Neogale frenata), the American ermine preys on mice, voles, shrews, youngcottontails,[7] 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.[8]
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.[8]
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.[1]
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.[8]
About 13 subspecies are known:
| Subspecies | Trinomial authority | Description | Range | Synonyms |
|---|---|---|---|---|
| Junean stoat M. r. alascensis. | Merriam, 1896 | Similar toM. r. richardsonii, but with a broader skull and more extensive white tips on the limbs[9] | Juneau, Alaska | |
| Vancouver Island stoat M. r. anguinae | Hall, 1932 | Vancouver Island | ||
| Western Great Lakes stoat M. r. bangsi | Hall, 1945 | The region west of theGreat Lakes | cicognani (Mearns, 1891) pusillus (Aughey, 1880) | |
| Bonaparte's stoat M. r. cigognanii
| Bonaparte, 1838 | A small subspecies with a dark brown summer coat; its skull is more lightly built than that ofrichardsonii.[10] | The region north and east of theGreat Lakes | pusilla (DeKay, 1842) vulgaris (Griffith, 1827) |
| M. r. fallenda | Hall, 1945 | |||
| M. r. gulosa | Hall, 1945 | |||
| M. r. initis | Hall, 1945 | |||
| M. r. invicta | Hall, 1945 | |||
| Southwestern stoat or New Mexico ermine M. r. muricus | Bangs, 1899 | The smallest subspecies ofrichardsonii.[2] | The southwestern extremity of the species' American range (Nevada,Utah,Colorado and other states) | leptus (Merriam, 1903) |
| Olympic stoat M. r. olympica | Hall, 1945 | TheOlympic Peninsula,Washington | ||
| Richardson's stoat M. r. richardsonii | Bonaparte, 1838 | Similar toM. r. cigognanii, but larger, with a dull chocolate brown summer coat[10] | Newfoundland,Labrador and nearly all of Canada (save for the ranges of other American stoat subspecies) | imperii (Barrett-Hamilton, 1904) microtis (J. A. Allen, 1903) mortigena (Bangs, 1913) |
| Baffin Island stoat M. r. semplei | Sutton and Hamilton, 1932 | Baffin Island and the adjacent parts of the mainland | labiata (Degerbøl, 1935) | |
| M. r. stratori | Merriam, 1896 |
The fur of ermine was valued by theTlingit and otherindigenous peoples of the Pacific Northwest Coast. They could be attached to traditional regalia and cedar bark hats as status symbols or made into shirts.[11]
