#1 Eurasian Stoat (Mustela erminea)

The Eurasian stoat, also known as the Beringian stoat, short-tailed weasel, ermine when in their white winter coat, or simply stoat, is native throughout much of Eurasia and the northern portions of North America. Of the mustelid family, the Eurasian stoat is one of the most famous and thoroughly researched species. They have been described by scholars, hikers, hunters and trappers, painters and authors worldwide, creating a vast goldmine of information.

For many years M. erminea was considered to be the one and only stoat species, until a 2021 study found two subspecies of M. erminea (the North American stoat and Haida stoat) to be distinct species.⁽¹⁾⁽²⁾ The Tundra stoat (M. e. arctica), Kodiak stoat (M. e. kadiacensis), Polar stoat (M. e. polaris), and (M. e. salva) appear to be the only subspecies of the Eurasian stoat found in North America under the current proposed revised taxonomy.⁽¹⁾

Appearance

During the summer months Eurasian stoats are russet in colour on the head and dorsal surface, with off-white (sometimes yellowish) underparts that run from the chin to along the abdomen, and have a distinguished black-tipped tail. The black brush that helps us telling the Eurasian stoat apart from any other weasel species in Eurasia is not only eye-catching to a human observer, it has evolved to function as a decoy to distract predators—especially birds of prey. This becomes even more efficient in winter, when northern weasels turn ermine: against the white background and when seen from above, ermines will appear like a flashing, dark dot thanks to their tail, keeping the pursuer from attacking the more vital parts of the body.

Thanks to the black tail brush the Eurasian stoat is seldom confused with any other species, but due to being often featured in media, it is easy to think there is only one ”basic” stoat in the world. Because of their wide distribution however, the Eurasian stoat has a great number of subspecies, each with their own distinct characteristics. Three subspecies are noteworthy for a closer look:

M. e. erminea– The Scandinavian stoat, native to Norway, Sweden and Denmark, as well as parts of Finland and the Kola Peninsula. Can be told apart from other subspecies by their small to medium size, lithe build, a very flat facial region with very large, wide-spaced eyes, tall ears, semi-long to short tail and paws that appear unusually large compared their overall proportions. The colour is rich chestnut to chocolate brown in summer, with white, cream or deep yellow underparts and paws. They always turn full ermine in winter.

M. e. stabilis– The typical stoat that many are familiar with, native to Great Britain and introduced to New Zealand. This is the largest and heaviest subspecies, weighing over twice as smaller subspecies on average and measures a few inches longer from the head to the rear. The overall appearance is bulky yet athletic, the eyes are small and the ears are shorter when compared to M. e. erminea (above), the tail is medium to long and the limbs are somewhat elongated too with strong shoulders. The colour varies from light brown tones of chestnut to red and orange in summer, with white, cream or light yellow underparts. Markings such as a dark brown facial mask or tiny cheek spots is not unusual. The paws have a varying degree of brown on top. Most stoats in England stay brown and a few turn only partially ermine. Full ermine is more common in Scotland.

M. e. hibernica– The Irish stoat. Medium in size, small eyes and ears, average build and a long, slim tail. Easily recognized by the distinctive patches across the lower part of the neck and front limbs, forming a broken band. The size of the patches varies between individuals. The colour is reddish brown in summer with a white or cream underside. The paws have a varying degree of brown on top. Stays brown all year round.

Winter coat

Their winter coat (referred to as ermine) is the same as the one found in the North American stoat, Haida stoat, least weasel, and long-tailed weasel. When temperatures drop and the nights become longer, certain subspecies of Eurasian stoat native to colder climates moult into their white winter coat. The tip of the tail always remains black.⁽³⁾

Albino Eurasian stoats

On rare occasions, a Eurasian stoat (like all other stoats and many other animals) can be born albino. The difference between an albino stoat and one that is in ermine, is that an albino one will have pink/red eyes, a pink nose, and typically no black-tipped tail. They would be seen in their white coats all year round, making them more vulnerable to predators when there is little to no snow about for natural camouflage.

To the untrained eye, an albino stoat can easily be confused for an albino ferret. To differentiate these two, stoats are smaller and slimmer overall, and have larger paws in relation to their size. Ferrets have boxy muzzles and skulls, pear-shaped bodies (in comparison) and coarser fur, especially on the back. Ferret tails are shorter and taper towards the tip. Ferrets also tend to arch their backs more when they move about.

Habitat

The Eurasian stoat is not very picky- they thrive where there are populations of small rodents or lagomorphs, cover where they can hide and where the conditions are not too extreme. Among the most typical habitats are farmland lined with hedgerows and stone walls, lowland forest, moorland, heathland, marshland, shoreline and mountains.

Behaviour

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Curiosity

A trait typically associated with mustelids that stoats take to another level. They have the habit of investigating about every hole or crack they come across, and will even dare to run up close to a human observer.⁽⁴⁾ Holes are of significant importance to the Eurasian stoat for multiple reasons: It is where they give birth, sleep, find food, cache food, and seek shelter from rivals, predators, and bad weather. The males live very hectic lives and travel over vast distances in spring and summer in search for mates, so it would make sense for them to check out any opportunity along the way. By contrast, the North American mink prefers more straight routes and often passes by a hole rather than taking a look inside, possibly because their preferred habitat is alongside rivers and streams, but the exact reason is unknown.⁽⁴⁾

Possible tool use

In Scandinavia, female stoats have been observed to move their young across lakes with the aid of a floating object, such as a flat piece of bark or dried cow manure.⁽⁵⁾ What counts as a tool, how advanced it needs to be and whether it needs to be manipulated or not is up to debate, but the use of an item in order to reach something of desire or achieve a task is noteworthy.

Reproduction

Being strictly solitary, the Eurasian stoat only seeks company from the opposite sex during the mating season. They perform a courtship dance where the tiny female leads the party, followed by the male. The pair leaves behind a scented trail that even humans are able sense, and is possible that it helps the sexes to find each other.⁽⁵⁾

Once the copulation process is over, the male leaves to search for other partners, while the female will be raising the young by herself. Due to delayed implication, the development of the embryos will temporarily stop and the litter, consisting of 6-8 kits on average, will be born the coming spring.

When it comes to spread their genes and secure coming generations, the Eurasian stoat has evolved an unique strategy, even by mammalian standards: The female kits reach sexual maturity and can be mated when they are only three weeks, blind and still suckling their mother. When a roving adult male visits the nest, he will encourage the mother, while the female kits are ones encouraging the male by emitting noises telling him they are ready.⁽⁶⁾ If not explained properly, this could easily give one the wrong idea of rape or abuse, which is not the case given how there is a form of “agreement” between both parts involved.⁽⁴⁾

This strategy seems to be as efficient as having several litters throughout the year, as the population numbers have been shown to bounce back after harsh times, such as when prey numbers are low. One example is the myxomatosis outbreak in the United Kingdom in the early 1950s, which decimated about 90% of the rabbits the stoats there are largely dependent on. The stoat population plummeted dramatically as a result, but they have increased steadily since then compared to more slow-breeding mustelids such as the Eurasian pine marten, which had almost been driven to extinction by a number of factors at that time and now needs help from a reintroduction program to increase their numbers.⁽⁶⁾⁽⁷⁾

Diet

Aside from birds and rabbits, Eurasian stoats prey on rodents, fish, eggs, insects, small reptiles and amphibians.⁽⁸⁾

Predators

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Possible declining numbers in North America

While there is currently no widespread conservation effort for the Eurasian stoat, a recent study suggests that their numbers could be declining in some parts of North America.⁽⁹⁾

Fur use

The white winter fur of Eurasian stoats has long been used in trimming coats and making stoles. This fur is referred to as “ermine”, and is the ancient symbol of the Duchy of Brittany, forming the earliest flag of that nation. Historically throughout Europe, ermine fur was considered to be a symbol of royalty and high status. However, due to animal rights concerns, faux fur is becoming more widely used and decreasing the demand for ermine pelts.⁽⁸⁾

Introduction to New Zealand

Eurasian stoats are known for taking down prey more than five times their size—using their teeth to bite into the necks of larger animals such as rabbits. For this skill, during the 1880s, Eurasian stoats were introduced to New Zealand in hopes of controlling the growing rabbit population. This may have seemed like a good idea to some at the time, but this decision has had a devastating effect on the native bird population,^(10)(6) prompting the New Zealand government to take action in eradicating them in their Predator Free 2050 programme.⁽¹¹⁾ Eurasian stoats are increasingly portrayed as vicious vermin that prey upon helpless birds, but it was humans who deliberately introduced them to the region. This is why we must always be cautious about introducing a foreign species to a new environment.

Common names of stoats in English (an identity crisis)

M. erminea was long considered to be the only species of stoat, until a 2021 study found two subspecies of M. erminea, the North American stoat (M. richardsonii) and Haida stoat (M. haidarum), to be distinct species.⁽¹⁾⁽²⁾ Since then the common names for these mustelids have become even more confusing, especially since there is little consistency among scientists on whether to refer to them as stoats, ermine, or short-tailed weasels. By far stoat is the most common English name for these animals.

Ermine

In the English language “ermine” is usually a term used to refer to any of the three species of stoats when in their white winter coat or pelt thereof, rather than the animals themselves. Given this association, it confuses some people when a stoat is called an ermine even while in their brown summer coat. Other creatures are also called ermine when sporting a black and white colouration such as certain types of moths, (Spilosoma lubricipeda, tautologically referred to as the white ermine, and the family Yponomeutidae).

Stoat versus short-tailed weasel

Stoats are called short-tailed weasels in North American English (though this seems to be more of a term used by scientists, since the average North American often refers to them as stoats) while stoat is preferred by the rest of the English-speaking world. The term short-tailed weasel is also a misnomer, given that the least weasel has a much shorter tail in both proportion and in terms of relative size than any other weasel species found in North America.

The Eurasian stoat is also simply called a “weasel” in Ireland where the least weasel is not known to live.

The “stoats and weasels” phrase

It is unclear why in England and New Zealand we continue to call one weasel a stoat while the other is simply called a weasel. The phrase “stoats and weasels” is commonly used when a stoat, being a member of the genus Mustela and subfamily Mustelinae, is a species of weasel. This phrase can be confusing for those not aware “weasel” is often used as a vague term to refer to the least weasel in these two countries. We have found that even some people who are raised in these nations are not aware of what weasel really means. When referring to these two mustelids in the same context “stoats and least weasels” would ultimately provide better clarity, especially for an international audience.

If you have ever read English literature such as The Wind in the Willows, Redwall, or Welkin Weasels and could not understand why some weasel-like species were called stoats, while other species with similar features were just called weasels, now you know! We were confused too. Just remember that least weasels in the UK (subspecies: M. n. vulgaris) are smaller than Eurasian stoats in the UK (subspecies: M. e. stabilis). They also do not have dark-tipped tails and do not change white for winter.

In social media

In recent years, wildlife artist Robert E. Fuller’s surveillance footage of Eurasian stoats and least weasels from surveillance cameras on his property have gone viral on many social discussion platforms. Perhaps the most well-known of these videos feature a group of young Eurasian stoats bouncing about on a blue trampoline. As usual with viral videos, few users give attribution to the original creator, so we wanted our readers to know one of the main sources for great Eurasian stoat surveillance. Among being an artist, Mr. Fuller has a deep appreciation for these mustelids and tries to educate the public about them. He is also known for raising and documenting a couple of orphaned Eurasian stoats he named Whisper and Stuart, as well as least weasels by the names Fidget, Ron, and Twiz.

Body length: 25–32 cm / 10–12 in (males), 17–27 cm / 6–10 in (females)
Tail length: 7.5–12 cm / 3.0–4.7 in (males), 6.5–10.6 cm / 2.6–4.2 in (females)
Weight: 67– 324 g / 2.3–11.4 oz (males), 25–260 g / 0.8–9 oz (females)
Lifespan: Up to 5 years (wild), up to 10 years (captivity)
Range: Widespread throughout North America, Eurasia, and introduced to New Zealand.
Conservation status: Least concern
Subfamily: Mustelinae
Recognised subspecies^(1)(12)

References

#2 Haida Stoat (Mustela haidarum)

The Haida stoat, also known as the short-tailed weasel, ermine when in their white winter coat, or simply stoat, is endemic to a few islands off the Pacific Northwest of North America, namely Haida Gwaii in Canada and the southern Alexander Archipelago in the U.S. state of Alaska.

This species is more commonly called the “Haida ermine” in the articles we reference, but we will not be referring to them as such on this site. When used in English, ermine usually refers to stoats when in their white winter coat or pelt thereof. The use of “Haida ermine” may confuse people in thinking that the terms ermine and stoat are not synonymous. It can also create confusion when the term ermine is used to refer to the species itself, especially when they are in their brown summer coat.

The three subspecies comprising the Haida stoat were originally considered subspecies of Eurasian stoat, but in 2013 they were recognised as distinct from any other stoat after examining their DNA and skull. Later, a 2021 study found them to together comprise a distinct species. The Haida stoat is presumed to have originated about 375,000 years ago, and is thought to be a result of hybrid speciation between the Eurasian stoat and North American stoat. The islands of Haida Gwaii and Prince of Wales are thought to have been glacial refugia during the Last Glacial Maximum, with both species of stoat being isolated on the islands and hybridising with one another while the ice sheets isolated them from the rest of the world—leading to the formation of a new species.^(1)(2)(3)

Appearance

The Haida stoat can be superficially distinguished from the North American and Eurasian stoat by their elongated skull.⁽²⁾

Winter coat

Their winter coat (referred to as ermine) is the same as that of the North American stoat, Eurasian stoat, and long-tailed weasel. The tip of the tail always remains black.

Habitat

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Behaviour

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Reproduction

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Diet

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Body length: N/A
Tail length: N/A
Weight: N/A
Lifespan: Unknown (wild), unknown (captivity)
Range: Haida Gwaii in Canada and the southern Alexander Archipelago in the U.S. state of Alaska.
Conservation status: Imperiled (haidarum), Vulnerable (celenda and seclusa)
Subfamily: Mustelinae
Recognised subspecies⁽¹⁾

References

#3 Indonesian Mountain Weasel (Mustela lutreolina)

The Indonesian mountain weasel is a poorly studied species found in the highlands on the islands of Java and Sumatra, Indonesia. They are island endemic and native to the Oriental biogeographic region.⁽¹⁾

Appearance

Being relatively large with an overall dark brown exterior, a bushy tail, and partially webbed paws, this weasel can easily be mistaken for a North American mink or European mink. They are however, lighter in build than either of those species, and have larger eyes and ears in proportion to the skull. Perhaps the simplest way of telling the difference geographically, is neither the North American mink nor European mink are found anywhere near Indonesia.

The Indonesian mountain weasel’s markings are also a bit different in shape and colour than that of the minks and can be distinguished by contrasting light yellow upper lip patches, chin, and a throat patch that extends down the throat. The patch is mostly angular, but can vary in shape and size between individuals. The fur is silky with a high sheen, giving a soft and elegant look.⁽²⁾⁽³⁾

Habitat

As their name suggests, they live in the forested mountainous regions of Java and Sumatra, Indonesia at elevations around 1,400–3,000 m (4593–9842 ft). Little else is known about their habitat use or preferred conditions due to a lack of surveys at high altitudes.⁽¹⁾⁽⁴⁾

Behaviour

Little is known about their behaviour. All of the few direct sightings and camera-trap records were by day, suggesting the species is diurnal.⁽¹⁾

Reproduction

Currently little is known about the mating system of the species.

Diet

Little is known about their diet, but they likely consume rodents like other weasel species.

Head and body length: 29.7–32.1 cm / 11.5–12.5 in
Tail length: 13.6–17 cm / 5–8 in
Weight: 295–340 g / 10–12 oz
Lifespan: Up to 10 years (wild), unknown (captivity)
Range: The islands of Java and Sumatra, Indonesia.
Conservation status: Least concern
Subfamily: Mustelinae
References

#4 Least Weasel (Mustela nivalis)

The least weasel is a species that holds many records, such as being the tiniest and the most specialised of all the weasels. In England and New Zealand the least weasel is often simply called a “weasel”,⁽¹⁾ particularly in reference to the common phrase “stoats and weasels” or tutorials explaining “how to tell the difference between a stoat and a weasel”. This has led to some of confusion in media given that stoats, being members of the genus Mustela and subfamily Mustelinae, are also a species of weasel.

The least weasel is the smallest weasel and member of Carnivora in the world, capable of passing through a wedding ring.⁽²⁾ While true, the species is also the most geographically widespread of the weasels, with a vast number of subspecies that have adapted to various conditions. This means the least weasel is not always the smallest by default, and some subspecies in warmer climates are often confused with rare species due to having an appearance or larger size that is very different from the standardised image we have of them from documentaries and other media.

Appearance

The least weasel appears particularly elegant, sleek and lithe in build, with a very blunt muzzle and small ears that seamlessly follows the overall shape without any notable protrusion from the rest. The tail is much shorter in relation to the body than in any other species of weasel as well as the limbs, making them seem closer to the ground when in motion as if they are sliding rather than bounding.

Beyond this, there is really no standard look, and it is necessary to mention a few subspecies to highlight their diversity:

• M. n. nivalis– A small to medium-sized subspecies, found in Norway, Sweden, the Baltic states, the southern Urals, in parts of Russia and in  Hokkaidō. Characterised by smooth fur, a short tail, rich chocolate-brown fur and a straight, clean transition between the upper part and the white underside. White in winter.

• M. n. vulgaris– The definite least weasel to many, known in the UK as the common weasel or simply the weasel. The subspecies was one of the mustelids introduced to New Zealand, but is also native to southern Voronezh and Kursk districts in Russia, Crimea, Ciscaucasia, and northern Caucasus. Characterised by medium size around the length of a finger, longer tail than m. n. nivalis, light reddish-brown fur, spots on each cheek and on the underside and a jagged transition between the upper-and underside. Least weasels in the UK stay brown all year round.

• M. n. numidica– The Mediterranean least weasel is the largest of the least. This subspecies is found in Morocco, Algeria, Egypt, Malta, Greece, the Azores Islands and Corsica. Due adaptations to a warmer climate and compared to other subspecies of least weasel, their outer extremities such as the tail and limbs have elongated. This, combined with their larger size can be easily mistaken for a Eurasian stoat or other larger weasel species. The fur is a light shade of brown on top with a yellowish cream underside. Stays brown all year round.

Winter coat

Their winter coat is similar to the North American stoat’s, Eurasian stoat’s, Haida stoat’s and long-tailed weasel’s—slightly longer than the summer coat, very dense and white, minus the black-tipped tail. Only certain subspecies native to colder climates undergo the moult cycle. Unlike stoats, in English they are usually not called ermine while in their winter coat.

Habitat

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Behaviour

While all weasels are experts on hunting small rodents, the least weasel is more dependent on them than any other species. They do not seem to be as adaptive as the stoat when it comes to switching between various types of prey, and while they can hunt larger animals like rabbits and birds they do not do it nearly as often.

Reproduction

Unlike the stoat and the long-tailed weasel, the least weasel does not have delayed implantation, but they have their own way and can have up to two litters throughout the year. Being the finely tuned specialists that they are, this allows them to have better chances at benefiting from the sporadic growth in the small rodent populations. However, like the numbers of burrowing rodents tend to swing drastically between highs and lows, so does the number of least weasels, and they will not even produce young at all when the prey numbers are down.

Least weasels mate all year round, although it commonly takes place in early spring. The female is left to raise the kits on her own shortly after, and typically chooses to den in a hole dug by her rodent prey or in a hollow log, furnished with hair from a meal or the previous resident. A single litter consists of 4-10 young which are born blind and deaf, but grow quickly: By autumn that same year, the female kits are already sexually mature and ready to have their first litter.

Diet

Primarily rodents such as field- and water voles, but also rabbits, birds, eggs, insects and berries.

Predators

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Introduction to New Zealand

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Possible declining numbers in North America

While there is currently no widespread conservation effort for the least weasel in North America, a recent study has found that their numbers appear to be declining at a concerning rate in some parts of the continent.⁽³⁾

In social media

Perhaps the most famous least weasel on the internet had its photo taken while riding on the back of a European green woodpecker (Picus viridis), though the least weasel is often misidentified as a Eurasian stoat. Amateur photographer Martin Le-May took the photograph in 2015 at Hornchurch Country Park in east London. The least weasel apparently attacked the woodpecker and held on as the bird took flight, only for both to soon safely land a short distance later and go their separate ways. Least weasels do not normally prey on woodpeckers but there is always an exception to the rule given the opportunity.

Body length: 13–26 cm / 5–10 in (males), 11.4–20.4 cm / 4.5–8.0 in (females)
Tail length: 1.2–8.7 cm / 0.5–3.4 in (males), 1.7–6 cm / 0.7–2.4 in (females)
Weight: 36–250 g / 1.3–8.8 oz (males), 29–117 g / 1.0–4.1 oz (females)
Lifespan: Up to 3 years (wild), up to 10 years (captivity)
Range: Widespread throughout the Northern Hemisphere.
Conservation status: Least concern
Subfamily: Mustelinae
Recognised subspecies⁽⁴⁾

References

#5 Malay Weasel (Mustela nudipes)

The Malay weasel, also known as the Malayan weasel or bare-footed weasel, is confined to three large land-masses of Sundaic Southeast Asia—the Thai-Malay peninsula and the islands of Sumatra and Borneo.⁽¹⁾

Appearance

Perhaps one of the most aesthetically pleasing species in terms of colouration, with a pure white head in stark contrast to the overall warm palette, with a golden brown body, orange-buff bib (throat and chest patch), and one third of the tail pale buff to white, matching the light head. The Malay weasel’s alternate—as well as their scientific name nudipes, accurately describes one of their most striking characteristics—that the soles around the paw pads are entirely hairless. Although the purpose of this characteristic is unknown. Their paws are also webbed. Furthermore, the Malay weasel has a somewhat shaggy appearance compared to the short and glossy coat of most weasels.

They are often confused with the Japanese marten because of their similar golden brown body and white-furred face. However, being a species of weasel, they are distinctively smaller and less bulky than the Japanese marten. Their nose is also typically pink, and the limbs of golden brown individuals are usually the same colour as the body, instead of all these parts being dark brown to blackish like on the Japanese marten.

Colour variations

In addition to the frequently observed coat colour shown in the photo above, the Malay weasel can also have a number of other coat colour and marking variations, which may be subspecies specific.⁽²⁾ The following YouTube videos are a few examples:

• Brown with facial markings. (not a ferret, as claimed in the video’s title)

• Brown with orange stripe, no major facial markings.

• Dark brown with silver stripe.

Habitat

The Malay weasel lives chiefly in tropical lowland forests, but they have also been recorded in swamp and montane forests, as well as plantations and high elevation montane scrub up to 1,700 m (5,600 ft).⁽¹⁾ They have also been found in both forested and deforested areas near urban areas.⁽³⁾

Behaviour

Little is known about their behaviour, but they are presumed to be solitary like most other weasel species.⁽⁴⁾

Reproduction

Currently little is known about the mating system of the species.

Diet

Little is known about their food habits, but like most weasels, they are presumed to prey on rodents, along with occasional small birds, eggs, lizards, and insects.⁽⁴⁾

Predators

Pythons are reported to be predators of the Malay weasel. They are also sometimes hunted by humans for food.⁽⁴⁾

Relationship with humans

Malayan weasels are sometimes killed by villagers for medicinal use, food, fur, trophy, for killing farmed poultry, and some level of incidental by-catch in snaring operations. In some areas, villagers welcome the species as a predator of crop-pest rats.⁽⁴⁾

Body length: 30–36 cm / 12–14 in
Tail length: 24–26 cm / 9.4–10.2 in
Weight: 598 g / 20.8 oz
Lifespan: Unknown (wild), unknown (captivity)
Range: The Sundaic sub-region of Southeast Asia.
Conservation status: Least concern
Subfamily: Mustelinae
Recognised subspecies⁽⁵⁾

References

#6 Mountain Weasel (Mustela altaica)

The mountain weasel, also known as the Altai weasel, pale weasel, or solongoi, primarily lives in high-altitude regions of Asia. They can be found in parts of Asia from Kazakhstan, Tibet, and the Himalayas to Mongolia, northeastern China, and southern Siberia.

Appearance

These weasels give off a delicate impression- they are sandy-brown on top and light yellow below with white paws. The face appears very defined with a dark nose and prominent zygomatic arches (cheek bones), framed with contrasting white whisker pads and chin.

Winter coat

Unlike most mustelids, the winter coat is a darker shade and more contrastful than the summer coat.

Habitat

The mountain weasel mainly lives in high-altitude environments at elevations up to 3,500 m (11,482 ft) or more, such as highland steppes, grassy woodlands, or above the timberline in heaps and stones. Near human habitations, they may dwell in rock crevices, tree trunks, and burrows of animals they previously hunted.⁽¹⁾⁽²⁾

Behaviour

There is little information about the behaviour of the mountain weasel. They are primarily nocturnal but may also occasionally hunt during the day. Like most weasels, they are capable of climbing and swimming and assumed to be solitary except when mating. Though presumed solitary, they communicate with each other vocally by making sounds to warn off possible predators, to protect territory, and when mating. Like most weasels, they emit a foul odour from their anal glands when threatened.^(2)(3)(4)

Reproduction

Little is known about the mating system of the mountain weasel, but according to observations in Kazakhstan, mating occurred in February or March. Young were seen around the start of May and the gestation period lasted around 30 to 49 days. Like most weasels of their genus, they are capable of delayed implantation. Litters of 1 to 8 were born, after which lactation lasted 2 months. The young would then live independent lives, but remained together until autumn.⁽²⁾

Diet

The mountain weasel is one of the primary predators of pikas, but it will also hunt small rodents in standard weasel-fashion like voles. Other prey include muskrats, ground squirrels, rabbits, small birds, reptiles, amphibians, and the occasional insect.⁽¹⁾ They are one of few mustelids that are regarded as beneficial to farmers, for their natural control of crop damaging pests.⁽²⁾

Predators

Their main predators are likely bird of prey.⁽¹⁾

Body length: 22–29 cm / 9–11.5 in (males), 22–25 cm / 9–10 in (females)
Tail length: 11–15 cm / 4–6 in (males), 9–12 cm /  3.5–5 in (females)
Weight: 217–350 g / 8–12 oz (males), 122–220 g / 4–8 oz (females)
Lifespan: Unknown (wild), unknown (captivity)
Range: Mountains of Asia, Russian central Asia, and Korea to northern India.
Conservation status: Near threatened
Subfamily: Mustelinae
Recognised subspecies⁽⁵⁾

References

#7 North American Stoat (Mustela richardsonii)

The North American stoat, also known as the American stoat, short-tailed weasel, ermine when in their white winter coat, or simply stoat, is a species native to much of North America.

This species is also called the American ermine in the articles we reference, but we will not be referring to them as such on this site. When used in English, ermine usually refers to stoats when in their white winter coat or pelt thereof. The use of “American ermine” may confuse people in thinking that the terms ermine and stoat are not synonymous. It can also create confusion when the term ermine is used to refer to the species itself, especially when they are in their brown summer coat.

This species was long considered a subspecies of the Eurasian stoat, until a 2021 study found them to be a distinct species, forming distinct genetic clades from erminea.⁽¹⁾⁽²⁾ Despite their name, the Eurasian stoat can still be found in parts of northern North America, according to iNaturalist map data,⁽³⁾ and it is difficult to distinguish between the two species.

Appearance

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Winter coat

Their winter coat (referred to as ermine) is the same as the one found in the Eurasian stoat, Haida stoat, least weasel, and long-tailed weasel. The tip of the tail always remains black.

Habitat

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Behaviour

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Reproduction

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Diet

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Possible declining numbers

While there is currently no widespread conservation effort for the North American stoat, a recent study suggests that their numbers could be declining in some parts of North America.⁽⁴⁾

Body length: N/A
Tail length: N/A
Weight: N/A
Lifespan: Unknown (wild), unknown (captivity)
Range: Most of North America
Conservation status: Not evaluated
Subfamily: Mustelinae
Recognised subspecies

References

#8 Stripe-Backed Weasel (Mustela strigidorsa)

The stripe-backed weasel is a poorly studied species that inhabits parts of Southeast Asia. Their prior English name back-striped weasel is often misspelled in amateur literature, the internet, and even in scientific literature as “black-striped weasel”.⁽¹⁾ For this reason, it has been recommended to refer to Mustela strigidorsa as the stripe-backed weasel,⁽²⁾ in line with other similarly-named animals.

Appearance

The stripe-backed weasel has a very distinguishing narrow, silvery dorsal streak extending from the top of their head down to the root of the tail. The dorsal surface is dark to reddish brown in colour, while a yellowish streak runs from the chest along the abdomen. The dorsal surface can vary in shades of brown, sometimes lighter on the head, or darker parallel to the dorsal streak. The chin and throat is pale to whitish in colour, and opens up and narrows as it moves down to the hind legs.⁽³⁾

Habitat

The stripe-backed weasel is thought to live primarily in the evergreen forests in the hills and mountains, but they have also been recorded in dense scrubs, secondary forests, grasslands, and farmland. It is unknown whether every location where the species are sighted are able to support population, or if the observations are due to dispersal from stable population zones.⁽¹⁾⁽⁴⁾

Behaviour

Like many weasels, the back-striped weasels are presumed to be diurnal and mostly solitary.⁽⁴⁾

Reproduction

Little is known about the reproduction of this extremely rare species. It is presumed to be similar to its closest taxonomical relatives. Unfortunately, it is still debated which species are close relatives to the stripe-backed weasel. Kurose et al. reported the North American mink to be more closely related to each other than other species of the genus Mustela.⁽⁵⁾ On the other hand, a review article on the stripe-backed weasel summarises that its phylogenetic relationship to other Mustela species is controversial.⁽¹⁾

Diet

Little is known about their dietary habits, but they likely consume rodents and other small mammals like most other weasels. In the Naga Hills, a stripe-backed weasel was seen attacking a bandicoot rat.⁽³⁾

Conservation

The stripe-backed weasel is protected in Thailand and listed as Endangered on the China Red List.⁽⁶⁾⁽⁷⁾ Participation in study of stripe-backed weasel habitat has been increasing. Before 1996, there were just two trap records of the species in the open literature collected by Abramov et al.⁽¹⁾ Between 1996 and 2014, Chutipong et al. has reported substantially more recent records of observations in Thailand, ostensibly due to the increasing number of capable observers in the area.⁽⁸⁾

Predators

Similar to other small carnivores, the stripe-backed weasel is subject to predation by larger carnivores. Their extreme rarity makes finding verifiable evidence of their predation difficult. There is little information on the influence of direct killing by humans on stripe-backed weasel populations, potentially simply due to their rarity.

Head and body length: 30–36 cm / 12–14 in
Tail length: 18–20 cm / 7.1–7.9 in
Weight: 700 g / 24.7 oz (juvenile males)
Lifespan: Unknown (wild), unknown (captivity)
Range: Southeastern Asia
Conservation status: Least concern
Subfamily: Mustelinae
References

#9 Yellow-Bellied Weasel (Mustela kathiah)

The yellow-bellied weasel is a poorly studied species found in Bhutan, Burma, China, India, Laos, Nepal, Pakistan, Thailand, and Vietnam.⁽¹⁾⁽²⁾

Appearance

While seemingly a classic insult, the species was simply named for its sulphur-yellow underbelly. The the rest of the pelt is a dark brown, with the upper lip, chin, and throat being lighter yellow-white in colour. The tail is more than half the length of the head and body. The foot pads are well developed and exposed with the soles of the hind paws being furless.⁽²⁾

Habitat

The yellow-bellied weasel in most of its range tends to dwell in evergreen forests and rugged highlands over 304.8 m (1,000 ft), and can occasionally be found above the timber line.⁽²⁾⁽³⁾

Behaviour

Currently little is known about their behaviour.

Reproduction

Currently little is known about the mating system of the species.

Diet

Yellow-bellied weasels prefer to consume mice, rats, voles and other small mammals. They will also prey on birds.⁽²⁾

Benefits to humans

The Nepalese have been known to keep yellow-bellied weasels as pets to manage rodent populations in their homes.⁽⁴⁾

Head and body length: 25.0–27.0 cm / 9.84–10.63 in
Tail length: 12–15 cm / 4.7–5.9 in
Weight: 1,560 g / 55 oz
Lifespan: Unknown (wild), unknown (captivity)
Range: Central and eastern Asia.
Conservation status: Least concern
Subfamily: Mustelinae
Recognised subspecies⁽⁵⁾

References

#10 African Striped Weasel (Poecilogale albinucha)
This species shares the common name “weasel”, but is not directly related to other species on this page except for L. patagonicus.

The African striped weasel is native to sub-Saharan Africa, and is one of the smallest on the continent. They can be found as far north as the Democratic Republic of the Congo and Kenya to as far south as southern South Africa. They are sometimes mistaken for a skunk or confused with the striped polecat.

Appearance

The African striped weasel has a short and broad snout and short ears. Their claws are curved. The top of the head is white, which continues downward as a broad stripe where there are black and white to pale yellowish stripes running down the back, the tail is completely white. As with most mustelids, males are larger than females.⁽¹⁾

Habitat

They can be found in a variety of habitats such as forests, grasslands, and marsh regions, but are most commonly found in savannahs. They usually live below 1,500 m (4,900 ft) elevation, but may be found as high as 2,200 m (7,200 ft).⁽²⁾⁽³⁾

Behaviour

The African striped weasel is nocturnal and lives primarily underground, though they may sometimes be found resting in hollow logs or rock crevices. Although mostly solitary, individuals will sometimes pair together to dig burrows. Sometimes they will take over the burrows of other animals such as rodents or mounds made by termites and modify them to suit their needs. The burrow varies in length but always has a rounded chamber where prey is cached for later consumption. The African striped weasel only leaves its burrow to hunt, and always brings kill back into the den before consuming or caching it. They kill prey by attacking the back of the neck then whipping their own bodies and kicking to stun and tear animal.⁽⁴⁾⁽⁵⁾

Males are aggressive towards the same sex, and will fluff their tails, make short cries and fake charges before the encounter escalates to fighting with bites, shaking, and aggressive shrieks if neither individual retreats.⁽¹⁾ Although a mostly silent animal, they have been known to have different vocalisations for distress, threat, defense, and greeting.⁽⁶⁾

Reproduction

Males may mate at 33 months of age and females may have their first litter at 19 months. Mating season is in the spring and summer, and includes three bouts of copulation lasting between 60 to 80 minutes each in a single 24 hour period.⁽¹⁾⁽⁷⁾ The gestation period lasts around 30 days and litters consists of 1-3 young.⁽¹⁾ The young are initially blind and hairless. They are fully weaned at about 11 weeks and reach adult size at 20 weeks. They are sexually mature by 8 months.⁽⁷⁾

Diet

Their diet consists of rodents, young birds, reptiles, and insects on occasion.^(3)(4)(8) Captive individuals have been observed to usually not eat the head, tail, legs, and dorsal skin of larger rodents.⁽⁶⁾

Predators

Poorly known. Presumably preyed upon by owls.⁽⁹⁾

Body length: 27–32 cm / 11–3 in
Tail length: 16–20 cm / 6.3–7.9 in
Weight: 339 g /12.0 oz (males),  251 g / 8.9 oz (females)
Lifespan: Unknown (wild), up to 5 years (captivity)
Range: Much of Africa south of the equator.
Conservation status: Least concern
Subfamily: Ictonychinae
References

#11 Patagonian Weasel (Lyncodon patagonicus)
This species shares the common name “weasel”, but is not directly related to other species on this page except for P. albinucha.

The Patagonian weasel is the only member of the genus Lyncodon,⁽¹⁾ and is one of the least known mustelids in South America. Its range is from the southern and western parts of Argentina into sections of Chile.⁽²⁾

Appearance

The fur is usually whiteish with some blended dark brown and black tones. There is a broad white to yellowish stripe that runs from the head along its neck and sides. As with most weasel-like mustelids, they have small ears, short legs, and a long body.

Habitat

Very little is known about their habitat. They supposedly inhabit herbaceous and shrub steppes in arid and semiarid areas.⁽²⁾ Another source suggests they are found in Pampas habitats that have light-coloured substrates excluding deserts. The den is built in a hole underground or under rocks or logs.⁽³⁾

Behaviour

The Patagonian weasel is has been reported to only be active at dusk and night. When cornered, the neck pelage will be erected as a defensive warning.⁽³⁾

Reproduction

Currently little is known about the mating system of the species.

Diet

Little is known about the Patagonian weasel’s diet, but they have been known to enter burrows of Ctenomys and Microcavia species, suggesting that may be their prey.⁽³⁾

Benefits to humans

The Patagonian weasel has been reported to be trained by some local ranchers to hunt and trap small terrestrial animals.⁽⁴⁾

Head and body length: 30–35 cm / 12–14 in
Tail length: 6–9 cm / 2.4–3.5 in
Weight: 225 g / 7.93 oz
Lifespan: Unknown (wild), unknown (captivity)
Range: Southern Argentina and southeastern Chile.
Conservation status: Least concern
Subfamily: Ictonychinae
Recognised subspecies⁽¹⁾

References

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