Stoat

The stoat, also known as the Eurasian ermine or ermine, is a species of mustelid native to Eurasia and the northern regions of North America. Because of its wide circumpolar distribution, it is listed as Least Concern on the IUCN Red List. The name ermine is used especially in its pure white winter coat of the stoat or its fur. Ermine fur was used in the 15th century by Catholic monarchs, who sometimes used it as the mozzetta cape. It has long been used on the ceremonial robes of members of the United Kingdom House of Lords. It was also used in capes on images such as the Infant Jesus of Prague.
The stoat was introduced into New Zealand in the late 19th century to control rabbits. However, they have had a devastating effect on native bird populations; as such, the species was nominated as one of the world's top 100 "worst invaders".

Etymology

The root word for "stoat" is likely either the Dutch word stout or the Gothic word ???????. According to John Guillim, in his Display of Heraldrie, the word "ermine" is likely derived from Armenia, the nation where it was thought the species originated, though other authors have linked it to the Norman French from the Teutonic harmin. This seems to come from the Lithuanian word šarmu. In North America it is called a short-tailed weasel. A male stoat is called a dog, hob, or jack, while a female is called a jill. The collective noun for stoats is either gang or pack.

Taxonomy

Formerly considered a single species with a very wide circumpolar range, a 2021 study split M. erminea into three species: M. erminea sensu stricto, M. richardsonii, and M. haidarum.

Subspecies

, 21 subspecies are recognized.

Image	Subspecies	Common name	Description	Range	Synonyms
	M. e. erminea Linnaeus, 1758	Northern stoat	Small-to-medium-sized with a relatively short and broad facial region	The Kola Peninsula, Scandinavia	hyberna maculata
	M. e. aestiva Kerr, 1792	Middle Russian stoat	Moderately sized with dark, tawny or chestnut summer fur	European Russia, Central and Western Europe	algiricus alpestris giganteus major
	M. e. arctica Merriam, 1826	Tundra stoat	Large, with a dark yellowish-brown summer coat, a deep yellow underbelly and a massive skull; it resembles the Eurasian stoat subspecies more closely than any other American stoat subspecies	Alaska, northwestern Canada, and the Arctic Archipelago	audax kadiacensis kadiacensis richardsonii
	M. e. augustidens Brown, 1908
	M. e. ferghanae Thomas, 1895	Fergana stoat	Small; very light, straw-brownish or greyish coat, which is short and soft. Light spots on the neck, sometimes forming a collar. It does not turn white in winter.	Tien Shan and Pamir-Alay mountains, Afghanistan, India, western Tibet and the adjacent parts of the Tien Shan in China	shnitnikovi whiteheadi
	M. e. hibernica Thomas and Barrett-Hamilton, 1895	Irish stoat	Larger than aestiva, but smaller than stabilis. Distinguished by the irregular pattern on the dividing line between the dark and pale fur on the flanks, though 13.5% of Irish stoats exhibit the more typical straight dividing line. They do not turn white in winter.	Ireland and Isle of Man
	M. e. kadiacensis Merriam, 1896	Kodiak stoat		Kodiak Island
	M. e. kaneii Baird, 1857	East Siberian stoat	Moderately sized, it is smaller than M. e. tobolica, with close similarities to M. e. arctica. The summer coat is relatively light coloured, with varying intensities of browning-yellow tinges.	Eastern Siberia and the Russian Far East including Kamchatka, except the Amur Oblast and Ussuriland, Transbaikalia and the Sayan Mountains. Also in Hokkaidō.	baturini digna kamtschatica kanei naumovi orientalis transbaikalica
	M. e. karaginensis Jurgenson, 1936	Karaginsky stoat	Very small, with a light chestnut-coloured summer coat	Karaginsky Island, along the eastern coast of Kamchatka
	M. e. lymani Hollister, 1912	Altai stoat	Moderately sized with less dense fur than M. e. tobolica. The summer coat consists of weakly developed reddish-brown tones. The skull is similar to that of M. e. aestiva.	The mountains of southern Siberia eastwards to Baikal and the contiguous parts of Mongolia
	M. e. martinoi Ellerman and Morrison-Scott, 1951				birulai
	M. e. minima Cavazza, 1912	Swiss stoat		Switzerland
	M. e. mongolica Ognev, 1928	Gobi stoat		The Govi-Altai Province
	M. e. nippon Cabrera, 1913	Japanese stoat		northern Honshū
	M. e. ognevi Jurgenson, 1932
	M. e. polaris Barrett-Hamilton, 1904	Polar stoat		Greenland
	M. e. ricinae Miller, 1907	Hebrides stoat		The Hebrides
	M. e. salva Hall, 1944
	M. e. stabilis Barrett-Hamilton, 1904	British stoat	Larger than mainland European stoats	Great Britain; introduced to New Zealand
	M. e. teberdina Korneev, 1941	Caucasian stoat	Small, with a coffee to reddish-tawny summer coat	The northern slope of the middle part of the main Caucasus range	balkarica
	M. e. tobolica Ognev, 1923	Tobolsk stoat	Large; it is somewhat larger than aestiva, with long and dense fur.	Western Siberia, eastwards to the Yenisei and Altai Mountains and in Kazakhstan

Evolution

The stoat's direct ancestor was Mustela palerminea, a common carnivore in central and eastern Europe during the Middle Pleistocene, that spread to North America during the late Blancan or early Irvingtonian. The stoat is the product of a process that began 5–7 million years ago, when northern forests were replaced by open grassland, thus prompting an explosive evolution of small, burrowing rodents. The stoat's ancestors were larger than the current form, and underwent a reduction in size as they exploited the new food source. The stoat first arose in Eurasia, shortly after the long-tailed weasel, which is in a different genus, arose as its mirror image in North America 2 million years ago. The stoat thrived during the Ice Age, as its small size and long body allowed it to easily operate beneath snow, as well as hunt in burrows. The stoat and the long-tailed weasel remained separated until 500,000 years ago, when falling sea levels exposed the Bering land bridge.
Fossilised stoat remains have been recovered from Denisova Cave. Combined phylogenetic analyses indicate the stoat's closest living relatives are the American ermine and Haida ermine, the latter of which partially descends from M. erminea. It is basal to most other members of Mustela, with only the yellow-bellied, Malayan, and back-striped weasels being more basal. The mountain weasel was formerly considered its closest relative although more recent analyses have found it to be significantly more derived. It was also previously thought to be allied with members of the genus Neogale such as the long-tailed weasel, but as those species have since been separated into a new genus, this is likely not the case.

Description

Build

The stoat is similar to the least weasel in general proportions, manner of posture, and movement, though the tail is relatively longer, always exceeding a third of the body length, though it is shorter than that of the long-tailed weasel. The stoat has an elongated neck, the head being set exceptionally far in front of the shoulders. The trunk is nearly cylindrical, and does not bulge at the abdomen. The greatest circumference of body is little
more than half its length. The skull, although very similar to that of the least weasel, is relatively longer, with a narrower braincase. The projections of the skull and teeth are weakly developed, but stronger than those of the least weasel. The eyes are round, black and protrude slightly. The whiskers are brown or white in colour, and very long. The ears are short, rounded and lie almost flattened against the skull. The claws are not retractable, and are large in proportion to the digits. Each foot has five toes. The male stoat has a curved baculum with a proximal knob that increases in weight as it ages. Fat is deposited primarily along the spine and kidneys, then on gut mesenteries, under the limbs and around the shoulders. The stoat has four pairs of nipples, though they are visible only in females.
The dimensions of the stoat are variable, but not as significantly as the least weasel's. Unusual among the Carnivora, the size of stoats tends to decrease proportionally with latitude, in contradiction to Bergmann's rule. Sexual dimorphism in size is pronounced, with males being roughly 25% larger than females and 1.5-2.0 times their weight. On average, males measure in body length, while females measure. The tail measures in males and in females. In males, the hind foot measures, while in females it is. The height of the ear measures in males and. The skulls of males measure in length, while those of females measure. Males average in weight, while females weigh less than.
The stoat has large anal scent glands measuring in males and smaller in females. Scent glands are also present on the cheeks, belly and flanks. Epidermal secretions, which are deposited during body rubbing, are chemically distinct from the products of the anal scent glands, which contain a higher proportion of volatile chemicals. When attacked or being aggressive, the stoat secretes the contents of its anal glands, giving rise to a strong, musky odour produced by several sulphuric compounds. The odour is distinct from that of least weasels.