The classification of weasels can be very confusing, as evolution has lead to a variety of species sharing the same anatomy. You’ll often hear mustelids referred to as the “weasel family”. However, this simplified terminology can cause confusion. Many mustelids (such as badgers, otters, wolverines etc.) are clearly not weasels. Some sources believe only members of the genus Mustela are regarded as “true” weasels.(1) The term “weasel” is also a common nickname given to any animal that’s just ‘slinky’ in appearance. All and all, it’s little wonder so many are confused as to just what a weasel is.

Weasels are the most slender and tiniest of the mustelids, and are primarily developed for hunting small rodents in their tunnels. Some of them can, however, attack and kill prey up to ten times their size, but not without risk. Weasels vary in length from 173 to 217 mm (6.8 to 8.5 in), females being smaller than the males, and usually have red or brown upper coats and white bellies. They have long, slender bodies, which enable them to follow their prey into burrows. Their tails may be from 34 to 52 mm (1.3 to 2.0 in) long.

Only three mustelids are known for changing to their white winter coats, and you will find all of them within this species list – the least weasel (Mustela nivalis), the long-tailed weasel (Mustela frenata), and the stoat (Mustela erminea).(2)

A Family Misunderstood

Classic myths and general fearmongering have made the weasel family the most misunderstood of all mustelids. Terms such as weasel out of and “weasel words” also haven’t helped their image. One of the most common, overstated conceptions about them is that they are simply ‘killing machines’ or ‘bloodthirsty animals that kill for pleasure’. Like all carnivores, weasels hunt to survive; this behavior is hardly unusual or unique in the animal kingdom for them to be solely defined by it. Small predators have it rough—living on the edge with threats around every corner, including their own metabolic rate. A constant race around the clock to stay warm and alive.(3) They have to be more intense than most to make it through the day, and unless we know the reasons for why they evolved to behave as they do, it’s easy to misinterpret their intentions. We’re not saying they don’t enjoy chasing their prey or enjoy the taste of their food, but it is not pure malice for fun.

Some would say another reason weasels are thought to kill for pleasure is due to the act of ‘surplus killing’; especially in regards to chickens. It is possible that multiple prey is killed so the weasel may return (or store) to consume their food at another time. It is this similar evolutionary programming that has enabled other species to survive.(4) Some weasels have a very high metabolism rate, and will perish if they do not eat frequently throughout the day.(5) It is possibly the case that weasels sometimes kill more than they can eat, but it is also possible the weasel is unable to return to eat the remainder of its kill due to the owner of the chicken coop scaring it off, or removing the chickens in its absence.

Common Misconceptions

You’ll often hear the term weasel spoken as though there is only one kind. Usually in British English “weasel” is used as a generic term to refer to the least weasel. This can cause a lot of confusion since there is technically no such animal as a generic weasel. There are however, many different species of weasels, and they all have their own unique range, sizes and fur patterns; including abilities and vulnerabilities relative to their respective climates.

Despite what we may have read in William Shakespeare’s plays,(6) weasels do not suck eggs.(7) In relation, the misnomer term “weasel word” first appeared in Stewart Chaplin’s 1900 short story “Stained Glass Political Platform”, in which weasel words were described as “words that suck the life out of the words next to them, just as a weasel sucks the egg and leaves the shell”.(8) The truth is weasels (more specifically stoats) have evolved a peculiar way to consume eggs. They make a small hole at the top, turn it so it lays in a horizontal position, and lick the liquid content when it starts flowing.(9) So essentially they drain eggs, not suck them. Seeing empty eggshells left behind gave rise to the myth that weasels suck eggs; which is an ill-conceived notion, given weasels don’t have prominent lips to be physically capable of that.

Weasels are not related to mongooses or meerkats. Though they look similar in ways, mongooses and meerkats actually have no relation to mustelids. They are both members of the family Herpestidae.


  1. B. Gilbert, The Weasel (1970); C. King, Weasels and Stoats (1989).
  2. Rich Landers “A peek at animals that turn white in winter” The Spokesman-Review (Jan. 10, 2012).
  3. Brown, James H., and Robert C. Lasiewski. “Metabolism of weasels: the cost of being long and thin.” Ecology 53.5 (1972): 939-943.
  4. Kruuk, Hans. “Surplus killing by carnivores.” Journal of Zoology 166.2 (1972): 233-244.
  5. King, Carolyn M. “The advantages and disadvantages of small size to weasels, Mustela species.” Carnivore behavior, ecology, and evolution. Springer, Boston, MA, 1989. 302-334.
  6. Freinkel, Lisa Myōbun. “Doing Time: Shakespeare’s Weasel, Chao-Chou’s Dog, and the Melancholy Lyric.” The Yearbook of Comparative Literature 57.1 (2011): 213-229.
  7. King, Carolyn M., and Roger A. Powell. The natural history of weasels and stoats: ecology, behavior, and management. Oxford University Press, 2006.
  8. Chaplin, Stewart. “Stained glass political Platform.” The Century Magazine (1900): 304-308.
  9. Steve Harris from BBC Wildlife magazine “How to identify bird egg thieves”.

(1) Altai Weasel / Mountain Weasel (Mustela altaica)

Photo by Karunakar Rayker

The mountain weasel primarily lives in high-altitud regions of Asia. From head to base of tail, length of males is about 220–280 mm (8.5–11 in). Males can weigh 230–340 g (8–12 oz), while females are smaller, measuring around 220–250 mm (8.5–10 in).

It hunts rodents, muskrats, rabbits, ground squirrels, small birds, eggs, lizards, frogs, fish; and occasionally insects. The mountain weasel is one of few mustelids that’s regarded as beneficial to farmers, for their natural control of crop damaging pests.

Conservation Status: Near Threatened

(2) Amazon Weasel / Tropical Weasel (Mustela africana)

Illustration by Hanna W.

Most sites that show a photograph of an Amazon weasel do not have the correct photo. In fact, we were unable to find a single website out there that had a photo of an actual Amazon weasel. For this reason we have used an illustration instead.

The Amazon weasel, also known as the tropical weasel, is a species native to South America. It was first identified from a museum specimen mislabeled as coming from Africa, hence the scientific name.

Conservation Status: Least Concern

(3) Back-Striped Weasel (Mustela strigidorsa)

Photo credit unknown.

The back-striped weasel, also called the stripe-backed weasel, is a species native to southeastern Asia. Their coats are dark/reddish brown in colour, with pale bellies. What is most distinguishing is the narrow, pale-coloured streak running down from their heads to their backs. They have a body length of around 30–36 cm (12–14 in).

Little is known about the diet and habits of the back-striped weasel, but it is believed they consume rodents and other small mammals like most other weasel species.

Conservation Status: Least Concern

(4) Colombian Weasel (Mustela felipei)

Photo by Juan Manuel de Roux

The Colombian weasel, also known as the Don Felipe’s weasel, is native to northern Ecuador and far eastern Colombia. It has an average length of 22 cm (8.7 in), and weighs between 120 and 150 g (4.2 and 5.3 oz). They have been observed to have webbed paws, which suggests they are perhaps semi-aquatic.

Little is known about this species due to few being seen. Its diet consists of fish, other small aquatic animals and small terrestrial mammals.

Conservation Status: Vulnerable

(5) Egyptian Weasel (Mustela subpalmata)

Photo credit unknown.

The Egyptian weasel is a species of weasel that lives in northern Egypt. It is rated “Least Concern” by the IUCN Red List.

Conservation Status: Least Concern

– Source from Wikipedia. The information above needs to be edited with our own words.

(6) Indonesian Mountain Weasel (Mustela lutreolina)

Photo credit unknown.

The Indonesian mountain weasel is a species that lives on the islands of Java and Sumatra in Indonesia at elevations over 1,000 metres (3,280 ft). They live in mountainous, tropical, and rain forest areas. Indonesian mountain weasels have a body length of 11–12 inches and a tail length of 5–6 inches. They are reddish-brown in color.

Conservation Status: Least Concern

– Source from Wikipedia. The information above needs to be edited with our own words.

(7) Japanese Weasel (Mustela itatsi)

Photo by Dibyendu Ash

The Japanese weasel is native to Japan where it occurs on the islands of Honshū, Kyūshū and Shikoku. It has been introduced to Hokkaidō and the Ryukyu Islands to control rodents and has also been introduced to Sakhalin island in Russia.

Conservation Status: Near Threatened

– Source from Wikipedia. The information above needs to be edited with our own words.

(8) Least Weasel / Common Weasel (Mustela nivalis)

Photo by Cecil Sanders (top), and Anatolii Vlasov (bottom)

The least weasel, common weasel, or simply weasel in the UK and much of the world, is the smallest member of the genus Mustela, family Mustelidae and order Carnivora.

Many are unaware that in far northern parts of the world, the least weasel’s coat becomes pure white during winter.

Average Lifespan: 2 years
Conservation Status: Least Concern

– Source from Wikipedia. The information above needs to be edited with our own words.

(9) Long-Tailed Weasel / Bridled Weasel  (Mustela frenata)

Photo by Keith and Kasia (top)

The long-tailed weasel, also known as the bridled weasel or big stoat, is a species of mustelid distributed from southern Canada throughout all the United States and Mexico, southward through all of Central America and into northern South America.

– Source from Wikipedia. The information above needs to be edited with our own words.

Size: 33-42 cm / 13-16.5 in (males), 28-35.5 cm / 11-14 in (females)
Weight: 226-401 g / 8-14.6 oz (males), 130-178 g / 4.5-6 oz (females)
Range: Southern Canada, all of the United States and Mexico, Central America and northern South America.
Conservation Status: Least Concern

(10) Malayan Weasel / Barefooted Weasel (Mustela nudipes)

Photo credit unknown.

The Malayan weasel lives in Brunei, Indonesia, Malaysia, and Thailand: on the islands of Sumatra and Borneo and the southern half of the Malay Peninsula. Malayan weasels have a body length of 12–14 inches and a tail length of 9.4–10.2 inches.

Conservation Status: Least Concern

– Source from Wikipedia. The information above needs to be edited with our own words.

(11) Siberian Weasel / Kolonok / Kolinsky (Mustela sibirica)

Photo by Alpsdake

The Siberian weasel is a medium-sized weasel native to Asia, where it is widely distributed and inhabits various forest habitats and open areas.

Conservation Status: Least Concern

– Source from Wikipedia. The information above needs to be edited with our own words.

(12) Stoat / Short-Tailed Weasel (Mustela erminea)

Photo by Steve Daniels (top), and Steven Hint (bottom)

The stoat, also known as the short-tailed weasel, is native throughout much of the Northern Hemisphere. They are found across Europe, Asia and North America. Stoats are russet in colour with an off-white belly, and have a distinguished black-tipped tail. During the winter months when temperatures drop and the nights become longer, stoats native to colder climates molt into their white winter (or ermine) coat. Although their coat turns pure white, the tip of their tail remains black.(1) The name ‘ermine’ is often misinterpreted for the name of the species, when it is in fact the name of the stoat’s white winter coat. A stoat is being “in ermine” while white.

On rare occasions, a stoat can be born albino. The difference between an albino stoat and one that’s in ermine, is that albino stoats have pink eyes, and no black-tipped tail.(2) 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.

Introduction to New Zealand

Stoats are known for taking down prey twice their size – using their sharp teeth to bite into the necks of larger animals such as rabbits. For this skill, during the 1870s and 1880s stoats were introduced to New Zealand to control the rabbit population. This proved effective for the time, but has since caused a devastating effect on the bird population in that country;(3) causing many conservationists to take action in eradicating them. They are increasingly portrayed as vicious pests that prey upon helpless birds, but it was the European colonists who introduced them to the region. This is why we must always be self-accountable and cautious about introducing a species to a new environment. Aside from birds and rabbits, stoats prey on rodents, fish, eggs, insects; small reptiles and amphibians.(4)

It is unclear why stoats are often excluded from weasels in many British literary titles. You’ll often hear “Stoats and Weasels” as a terminology when there’s literally no reason to separate stoats, since they’re all members of the same family. It is possible the reason is due to stoats being the only species in the weasel family whose name does not end with ‘weasel’ in British English. The term short-tailed weasel is mostly used in North America, while stoat is commonly used in Britain.

Size: 25-35 cm / 10-14 in (males), 17-27 cm / 6-10 in (females)
Weight: 200-500 g / 7-17.6 oz (males), 5-9.8 oz (females)
Average Lifespan: 2-5 years
Range: Widespread throughout the Northern Hemisphere, and introduced to New Zealand.
Conservation Status: Least Concern

  1. Harris, S., and D. W. Yalden. “Mammals of the British Isles, 4th edn (Southampton: Mammal Society).” (2008). p. 457
  2. Fairley, J. S. “New data on the Irish stoat.” The Irish Naturalists’ Journal (1971): 49-57.
  3. King, Carolyn Immigrant killers: introduced predators and the conservation of birds in New Zealand. Oxford University Press, 1984.
  4. Heptner, V. G., and A. A. Sludskii. “Mammals of the Soviet Union. Vol. II, part 1b, Carnivores (Mustelidae and Procyonidae).” Washington, DC: Smithsonian Institution Libraries and National Science Foundation (2002). p. 1018

(13) Yellow-Bellied Weasel  (Mustela kathiah)

Photo by Rejaul karim.rk

The yellow-bellied weasel lives in the pine forests of Bhutan, China, India, Laos, Myanmar, Nepal, Thailand, and Vietnam.

Conservation Status: Least Concern

– Source from Wikipedia. The information above needs to be edited with our own words.

Although the following are called ‘weasels’, they are not closely related to the weasel species above.

(14) African Striped Weasel (Poecilogale albinucha) – Genus Poecilogale

Photo by Devonpike

The African striped weasel is native to sub-Saharan Africa, and is one of the smallest carnivores on the continent. It is black and white (or yellowish) in colour and closely resembles a skunk. They have a body length of around 300 mm (11 inches), and weight between 250-350 grams (9-12 ounces).  Males are slightly larger the females.

Their diet consists of rodents, young birds, reptiles, and insects on occasion.

Conservation Status: Least Concern

(15) Patagonian Weasel (Lyncodon patagonicus) – Genus Lyncodon

Photo credit unknown.

The Patagonian weasel is the only member of the genus Lyncodon,(1) and is one of the least known mustelids in South America. Very little is known about this species, but it can be found in both southern Argentina and southeastern Chile. It inhabits herbaceous and shrub steppes in arid and semiarid areas.(2)(3)(4)(5)

Similar to the regional greater grison and tayra, the Patagonian weasel has been reported to be kept as a trained pet by some locals to hunt and trap small terrestrial animals; mainly rodents.(6)

Size: 30-35 cm / 12-14 in (males)
Weight: 225 g / 7,93 oz (males)
Average Lifespan: Not reported.
Range: Southern Argentina and southeastern Chile.
Conservation Status: Least Concern

  1. Wilson, Don E., and DeeAnn M. Reeder, eds. Mammal species of the world: a taxonomic and geographic reference. Vol. 1. JHU Press, 2005.
  2. Larivière, S., and A. P. Jennings. “Mustelidae (weasels and relatives).” Handbook of the mammals of the world 1 (2009): 564-656.
  3. Osgood, Wilfred Hudson. The mammals of Chile. Field Museum of Natural History, 1943.
  4. Prevosti, F. J., and U. F. J. Pardiñas. “Variaciones corológicas de Lyncodon patagonicus (Carnivora, Mustelidae) durante el Cuaternario.” Mastozoología Neotropical 8.1 (2001): 21-39.
  5. Schiaffini, Mauro I., et al. “Distribution of Lyncodon patagonicus (Carnivora, Mustelidae): changes from the Last Glacial Maximum to the present.” Journal of Mammalogy 94.2 (2013): 339-350.
  6. Nowak, Ronald M., and Ernest Pillsbury Walker. Walker’s Mammals of the World. Vol. 1. JHU press, 1999.

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