Eurasian Stoat

The stoat has a circumboreal range throughout North America, Europe, and Asia. The stoat in Europe is found as far south as 41ºN in Portugal, and inhabits most islands with the exception of Iceland, Svalbard, the Mediterranean islands and some small North Atlantic islands. In Japan, it is present in central mountains (northern and central Japanese Alps) to northern part of Honshu (primarily above 1,200 m) and Hokkaido. Its vertical range is from sea level to 3,000 m (9,800 ft). In North America, it is found throughout Alaska and western Yukon to most of Arctic Canada east to Greenland. Throughout the rest of North America, as well as parts of Nunavut, including Baffin Island and some islands in southeast Alaska, it is replaced by M. richardsonii. Stoats have been present in Orkney, north of Scotland, since 2010, where they are a predator of the Orkney vole and native bird populations. In 2018, a stoat eradication plan, the Orkney Native Wildlife Project, was applied across the archipelago. By 2024 the Orkney Native Wildlife Project had spent £7.9m trapping more than 6,300 stoats, and facilitating recovery in the islands' populations of Orkney voles, curlews, hen harriers and waders.

Introduction to New Zealand. Stoats were introduced into New Zealand during the late 19th century to control rabbits and hares, but are now a major threat to native bird populations. …

In the Northern Hemisphere, mating occurs in the April–July period. In spring, the male's testes are enlarged, a process accompanied by an increase of testosterone concentration in the plasma. Spermatogenesis occurs in December, and the males are fertile from May to August, after which the testes regress. Female stoats are usually only in heat for a brief period, which is triggered by changes in day length. Copulation can last as long as 1 hour. Stoats are not monogamous, with litters often being of mixed paternity. Stoats undergo embryonic diapause, meaning that the embryo does not immediately implant in the uterus after fertilization, but rather lies dormant for a period of nine to ten months. The gestation period is therefore variable but typically around 300 days, and after mating in the summer, the offspring will not be born until the following spring – adult female stoats spend almost all their lives either pregnant or in heat. Females can reabsorb embryos and in the event of a severe winter they may reabsorb their entire litter. Males play no part in rearing the young, which are born blind, deaf, toothless and covered in fine white or pinkish down. The milk teeth erupt after three weeks, and solid food is eaten after four weeks. The eyes open after five to six weeks, with the black tail-tip appearing a week later. Lactation ends after 12 weeks. …

The root word for "stoat" is likely either the Dutch word stout ("bold") or the Gothic word 𐍃𐍄𐌰𐌿𐍄𐌰𐌽 (stautan, "to push"). 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 (Anglo-Saxon hearma). 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.