Weasels

The classification of weasels can be very confusing, as evolution has lead to a variety of species sharing the same anatomy. The family Mustelidae is often simply referred to as the “weasel family”. However, this terminology can be misleading in the English language, given many distinctive mustelids (such as badgers, martens, the tayra and the wolverine) are related to weasels, or in some cases ‘weasel-like’, but are not actually 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.

Depending on the subspecies, 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 (M. nivalis), the long-tailed weasel (M. frenata), and the stoat (M. erminea).(2)

Terminology

You’ll often hear the word “weasel” spoken as though there is only one kind. Usually in British English “weasel” is used as a common name to refer to the least weasel. Although this term isn’t incorrect, its overuse has lead many people to believe there is only one type of weasel in existence, or that the species is somehow more ‘weasel-like’ compared to other weasels. Truth is there are many different species and subspecies of weasels, many of which have their own unique features, size and range; including abilities and vulnerabilities relative to their respective climates.

A family misunderstood

Classic myths and general fearmongering have made the weasel family the most misunderstood of all mustelids. The common expression weasel out of and misnomer term “weasel words” also haven’t helped their image. In addition, people frequently attribute human emotions or behaviour onto weasels, claiming they are simply “mass murderers” or “bloodthirsty” animals that kill for pleasure. Like all carnivores, weasels hunt to survive; this behaviour is hardly unusual or unique in the animal kingdom for them to be superficially 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.

Surplus killing

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. Though the exact reason is inconclusive, it is possible that multiple prey is killed so the weasel may return (or store) to consume its food at another time. It is this similar evolutionary programming that has enabled other species to survive.(4) Some weasels have a very high metabolic 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 killed chickens in its absence.

Common misconceptions

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 a bizarre notion, given weasels don’t have prominent lips to be physically capable of that.

References

  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.

Appearance

Conservation Status: Near Threatened

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

Illustration by Hanna W.

The Amazon weasel, also known as the tropical weasel, is a species only found in South America. Although the full extent of their range is unknown, the Amazon weasel is found in humid areas, mainly in forests near the banks of rivers in the Amazon basin.(1) Early scientific records inaccurately described the Amazon weasel’s native range as Africa, which led to its misleading scientific name.(2) This only adds to the complex taxonomy of the mustelid family.

Appearance

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 created an illustration instead. Their fur varies from reddish to dark brown on the dorsal surface, and is pale orange-tan on the underparts. A stripe of the same colour as that on the dorsal surface runs down the centre of the chest and throat.(1)

Diet and behaviour

Little is known about the diet of the Amazon weasel, but it likely consumes rodents and other small mammals. They have been reported to construct burrows in the stumps of hollow trees.(1)

Size: 43—52 cm / 17—20 in, with a tail length of 16—21 cm / 6.3—8.3 in (males)
Weight: 700 g / 1.5 lb (males)
Average Lifespan: Not reported.
Range: Brazil, Ecuador, Peru and northern Bolivia.
Conservation Status: Least Concern
References

  1. Emmons, Louise, and François Feer. Neotropical rainforest mammals: a field guide. No. Sirsi) i9780226207193. 1997.
  2. Ramírez-Chaves, Héctor E., Heidi Liliana Arango-Guerra, and Bruce D. Patterson. “Mustela africana (Carnivora: Mustelidae).” Mammalian Species 46.917 (2014): 110-115.

(3) Back-Striped Weasel (Mustela strigidorsa)

Photo credit unknown.

The back-striped weasel, also called the stripe-backed weasel, is a species that inhabits southeastern Asia. It is thought to live primarily in the evergreen forests in the hills and mountains, but has also been recorded in dense scrubs, secondary forests, grasslands, and farmland.(1) Like many weasels, the back-striped weasel is presumed to be diurnal and mostly solitary.

Appearance

The back-striped weasel has a very distinguishing narrow, silvery dorsal streak extending from the top of its head down to the root of its 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. Its chin and throat is pale to whitish in colour, and opens up and narrows as it moves down to its hind legs.(2)

Diet

With limited research on the back-striped weasel, little is known about their diet, but it likely consumes rodents and other small mammals like most other weasels.

Conservation

The back-striped weasel is protected in Thailand and listed as Endangered on the China Red List.(3)(4)

Size: 30–36 cm / 12–14 in, with a tail length of 18–20 cm / 7.1–7.9 in (males)
Weight: 700 g / 1.5 lb (males)
Average Lifespan: Not reported.
Range: Southeastern Asia
Conservation Status: Least Concern
References

  1. Abramov, A. V., et al. “The stripe‐backed weasel Mustela strigidorsa: taxonomy, ecology, distribution and status.” Mammal Review 38.4 (2008): 247-266.
  2. Pocock, R. I. (1941). “Mustela strigidorsa Gray. The Back-striped Weasel”The Fauna of British India, including Ceylon and Burma. Mammalia Vol. II. Carnivora (suborders Aeluroidae (part) and Arctoidae). London: Taylor and Francis, Ltd. pp. 376–380.
  3. Roberton, S., et al. “Mustela strigidorsa. The IUCN Red List of Threatened Species 2016: e. T14027A45201218.” (2016).
  4. Wang, S. and Xie, Y. 2004. China Species Red List. Vol. 1 Red List. Higher Education Press, Beijing, China.

(4) Colombian Weasel (Mustela felipei)

Photo by Juan Manuel de Roux

The Colombian weasel, also known as the Don Felipe’s weasel, is a very rare weasel native to northern Ecuador and far eastern Colombia. Both its scientific and alternative common name honours the mammalogist Philip “Don Felipe” Hershkovitz.(1)

Appearance

The dorsal surface and tail are blackish-brown, while the underparts are orange-buff. There is also a distinguish ventral spot on its neck that’s the same color as the dorsum. Colombian weasels are observed to have webbed paws, which suggests they are perhaps semi-aquatic.(1)(2)(3)

Diet and behaviour

Little is known about the diet of the Colombian weasel, but due to their webbed paws and occurrence in riparian habitats, they are assumed to eat fish and other aquatic organisms, in addition to terrestrial small mammals, birds and insects.(4)(5) Like other weasels, they are likely to be mainly solitary and sedentary.(6)(7)

Size: 28—38 mm / 11—14.9 in (males)
Weight: 120—150 g / 4.23—5.29 oz (males)
Average Lifespan: 1 to 6 years
Range: Western Colombia to northern Ecuador.
Conservation Status: Vulnerable
References

  1. Izor, Robert J., and Luis de la Torre. “A new species of weasel (Mustela) from the highlands of Colombia, with comments on the evolution and distribution of South American weasels.” Journal of Mammalogy 59.1 (1978): 92-102.
  2. Bernal, E. 2004. Plan de Desarrollo Chivatá-Boyacá. Alcaldía Municipal de Chivatá. Chivata, 13: 126-128.
  3. McKelvey, K., K. Aubry, M. Schwartz. 2007. Using anecdotal occurrence data for rare or elusive species: the illusion of reality and a call for evidentiary standards.. species of Mustela, 12: 121-126.
  4. Alberico, M. “New locality record for the Colombian weasel (Mustela felipei).” Small Carnivore Conservation 10 (1994): 16-17.
  5. Eisenberg, J., K. Redford. 1999. Mammals of the Neotropics: The Central Neotropics: Ecuador, Peru, Bolivia, Brazil. Chicago: University of Chicago Press.
  6. Bernal, E. 2004. Plan de Desarrollo Chivatá-Boyacá. Alcaldía Municipal de Chivatá. Chivata, 13: 126-128.
  7. Nowak, R. 2005. Walker’s Carnivores of the world. Pp. 300-355 in Mustela. Baltimore, USA and London, UK.: Johns Hopkins University Press.

(5) Egyptian Weasel (Mustela subpalmata)

Photo credit unknown.

The Egyptian weasel is a species of weasel that lives in northern Egypt.

Appearance

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.

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

Appearance

They are reddish-brown in color, with light yellowish patches on the upper lip and a corresponding light chin and large throat patch.

Conservation Status: Least Concern

(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.

Appearance

Conservation Status: Near Threatened

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

(8) Least 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.

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

Appearance

Lifespan: 1-2 years on average, 4-10 years at most
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.

Appearance

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.

Appearance

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.

Appearance

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, or ermine when in its white winter coat, is native throughout much of the Northern Hemisphere. They are found across Europe, Asia and North America.

Appearance

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) 

Introduction to New Zealand

Stoats are known for taking down prey more than five times 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 act may have proved effective for the time, but it has since only resulted in a devastating effect on the bird population today,(2) prompting the New Zealand government to take action in eradicating them in their Predator Free 2050 programme.(3) Stoats 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. We understand the dire situation to save the native birds, but it’s unfortunate that once again animals are killed to make up for human irresponsibility.

Diet

Aside from birds and rabbits, stoats prey on rodents, fish, eggs, insects, small reptiles and amphibians.(4)

Albino stoats

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.(5) 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.

Terminology

In English the name “ermine” is a term used to refer to the stoat’s white winter coat—a stoat is being “in ermine” while white. There are actually several animals that are refereed to as ermine when sporting a black and white colouration, such as ermine moths.

The term “short-tailed weasel” is primarily used in North American English to refer to the stoat, while “stoat” is commonly used in British English. It is unclear however, why stoats are often excluded from weasels in British English. The term“stoats and weasels” is often used, when there’s no reason to separate stoats, since a stoat is just a species of weasel. In British English “weasel” is most often used as a generic term to refer to the least weasel. In other words, “stoats and weasels” often means “stoats and least weasels”.

Size: 25-35 cm / 10-14 in (males), 17-27 cm / 6-10 in (females)
Weight: 258-450 g / 9-15.8 oz (males), 90-180 g / 3-6.3 oz (females)
Lifespan: 1-2 years on average, 4-10 years at most.
Range: Widespread throughout the Northern Hemisphere, and introduced to New Zealand.
Conservation Status: Least Concern
References

  1. Harris, S., and D. W. Yalden. “Mammals of the British Isles, 4th edn (Southampton: Mammal Society).” (2008). p. 457
  2. King, Carolyn Immigrant killers: introduced predators and the conservation of birds in New Zealand. Oxford University Press, 1984.
  3. Linklater, Wayne, and Jamie Steer. “Predator Free 2050: A flawed conservation policy displaces higher priorities and better, evidence‐based alternatives.” Conservation Letters 11.6 (2018): e12593.
  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
  5. Fairley, J. S. “New data on the Irish stoat.” The Irish Naturalists’ Journal (1971): 49-57.

(13) Yellow-Bellied Weasel  (Mustela kathiah)

Photo by Jitendra Bhatia

The yellow-bellied weasel lives in the pine forests of Bhutan, Burma, China, India, Laos, Nepal, Pakistan, Thailand and Vietnam.(1)

Appearance

The species is named for its deep yellow-colored underbelly, while the rest of its pelt is dark brown. The upper lip, chin and throat are a lighter yellow-white colour.(2)

Diet

Yellow-bellied weasels prefer to consume mice, rats, voles and other small mammals. They will also prey on birds.(3)(4)

Benefits to humans

The Nepalese have been known to keep yellow-bellied weasels as pets to manage rodent populations in their homes. It is also reported that they have even been trained to attack geese, goats, and sheep for sport.(2)(4)(5)

Size: 250—270 mm / 9.84—10.63 in (males)
Weight: 1.56 kg / 3.44 lb (males)
Average Lifespan: Not reported.
Range: Central and eastern Asia.
Conservation Status: Least Concern
References

  1. “Yellow-bellied weasel”Thai National Parks.
  2. Hussain, S. A. “Mustelids, viverrids and herpestids of India: species profile and conservation status.” ENVIS Bulletin 2.2 (1999): 1-38.
  3. Nowak, J. L., and John L. Paradiso. “Walker’s mammals of the world.” JOHNS HOPKINS UNIVERSTY PRESS, BALTIMORE(USA). 1983. (1983).
  4. Jha, A. “Status of the weasel family in Sikkim.” Tigerpaper (FAO) (1999).
  5. Sterndale, Robert Armitage. Natural history of the Mammalia of India and Ceylon. Thacker, Spink, 1884.


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.

Appearance

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)

Appearance

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
References

  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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