WEASELS: CHARACTERISTICS, BEHAVIOR, SPECIES

WEASELS

weasels

Weasels belong to the Order Carnivora and the Family Mustelidae. Although they are small in size they are fearless predators that will eat just about any small animal they can catch. They are mostly nocturnal but are sometimes seen in the day. Erin Blakemore wrote in National Geographic History, “They may be cute, but weasels aren’t exactly known for their propriety. The crafty animals are shrewd thieves with a carnivorous diet, a protective sense of territory, and the ability to ward off would-be predators with pungent odors and shriek-like sounds. [Source: Erin Blakemore, National Geographic History, March 28, 2024; Richard Conniff, Smithsonian]

Zoologists recognize about a dozen and half species of weasel worldwide. The most well known ones are the short-tailed weasel (also known as ermine or stoat), the least weasel (indigenous to Europe and Asia and introduced to North America and New Zealand), the long-tailed weasel (found mostly in North America).

Weasels rarely live more than a year. They are small, long and slender. They range in length from 13 centimeters to 30 centimeters (5 inches to 12 inches) and usually weigh less than half a kilograms (12 ounces). They have short legs, broad flat heads, long necks and powerful jaw muscles and long, sharp canine teeth. Males are generally 25 to 35 centimeters in length not including the tail and weigh up half a kilogram. Females are usually less than half this size. Like their relative the skunk, weasels posses an anal gland that can spray a nasty smelling liquid that is not as bad as that of skunk but still pretty bad. The spray is used primally as a last measure of defense.

Weasels are feed on by hawks, owls, eagles, lynx and wolves. But these animals engage weasels at their own peril. Once, a weasel was captured by a hawk and taken into the air. A witness observed the hawk take off and then plummet to the ground. I was found the bird had died from a fatal weasel bite to the chest. Another time, an eagle was found with a bleached weasel skull with its teeth permanently clenched into the bird’s neck. Weasels are also preyed on by parasitic worms that eat their brain. Some scientist believe that these parasites many explain their "dance for death" behavior.

Book: “Natural History of Weasels and Stoats” by Carolyn King, Weasel Expert at Oxford University.

Mustelids

Weasels are mustelids (Mustelidae), a diverse family of carnivoran mammals, including weasels, badgers, otters, stoats, mink, sables, ermine, fishers, ferrets, polecats, martens, grisons, wolverines, hog badgers, honey badgers and ferret badgers. Mustelids, make up the largest family within Carnivora with about 66 to 70 species in eight or nine subfamilies and 22 genera. Skunks were considered a subfamily within Mustelidae, but recent molecular evidence has led their removal from the mustelid group. They are now recognized as a their own single family, Mephitidae. [Source: Wikipedia, Matt Wund, Animal Diversity Web (ADW) |=|]

Mustelids inhabit all continents except Australia and Antarctica, and do not live on Madagascar or oceanic islands. They are found in diverse terrestrial and aquatic habitats in temperate, tropical and polar environments — in tundra, taiga (boreal forest), conifer forests, temperate forests, deserts, dune areas, savanna, grasslands, steppe, chaparral forests, tropical and temperate rainforests, scrub forests, mountains, lakes, ponds, rivers, streams. coastal brackish water, wetlands such as marshes, swamps and bogs, suburban areas, farms, orchard and areas near rivers, estuaries and intertidal (littoral) zones.

Mustelids vary greatly in behavior. They are mainly carnivorous and exploit a wide diversity of both vertebrate and invertebrate prey, with different members specializing in certain kinds of prey. Most mustelids are adept hunters with some weasels able take prey much larger than themselves. Many species hunt in burrows and crevices; some species have evolved to become adept at climbing trees (such as martens) or swimming (such as otters and mink) in search of prey. Wolverines can crush bones as thick as the femur of a moose to get at the marrow, and have been seen attempting to drive bears away from their kills. Mustelids typically live between five and 20 years in the wild. |=|

Weasel Species by Subgenus

Mustela Subgenus: .
Mountain weasel (Mustela altaica Pallas, 1811) live in Northern and Southern Asia.
Missing-toothed pygmy weasel (Mustela aistoodonnivalis Wu & Kao, 1991) live in Shaanxi and Sichuan, China.
Stoat (Mustela erminea Linnaeus, 1758) are also known as Beringian ermine, Eurasian ermine, and short-tailed weasel. They live in Europe and Northern Asia, Arctic Canada and Alaska, Southern Asia, (non-native), New Zealand (non-native).

MustelidaePhylogeneticTree

Haida ermine (Mustela haidarum Preble, 1898) are also knownas Haida Gwaii. They live in British Columbia, Canada and Alexander Archipelago, Alaska.
Yellow-bellied weasel (Mustela kathiah Hodgson, 1835) live in Southern Asia.
Least weasel (Mustela nivalis Linnaeus, 1766) live in Europe, North Africa and Northern Asia, North America, Southern Asia (non-native), New Zealand (non-native).
American ermine (Mustela richardsonii Bonaparte, 1838) live in most of North America south of Alaska and the Arctic Circle; eastern Nunavut and Baffin Island.

Lutreola Subgenus: .
Japanese weasel (Mustela itatsi Temminck, 1844) live in Japan and formerly Sakhalin Island, Russia.
European mink (Mustela lutreola, (Linnaeus, 1761) live in Europe.
Indonesian mountain weasel (Mustela lutreolina Robinson and Thomas, 1917) live in Southeastern Asia.
Malayan weasel (Mustela nudipes Desmarest, 1822) live in Southeastern Asia.
Siberian weasel (Mustela sibirica Pallas, 1773) live in Europe and Northern Asia, Southern Asia.
Back-striped weasel (Mustela strigidorsa Gray, 1855) live in Southern Asia.

Putorius Subgenus: .
Steppe polecat (Mustela eversmanii, Lesson, 1827) live in Southeast Europe and Northern Asia, Southern Asia.
Domestic ferret (Mustela furo Linnaeus, 1758) live worldwide (domesticated); New Zealand (non-native).
European polecat (Mustela putorius Linnaeus, 1758) live in Europe, North Africa and Northern Asia.
Black-footed ferret (Mustela nigripes, Audubon and Bachman, 1851) live in North America.

Where Weasel Species Live

Northern Hemisphere .
Stoat (Mustela erminea Linnaeus, 1758) are also known as Beringian ermine, Eurasian ermine, and short-tailed weasel. They live inEurope and Northern Asia, Arctic Canada and Alaska, Southern Asia (non-native), New Zealand (non-native).
Least weasel (Mustela nivalis Linnaeus, 1766) live in Europe, North Africa and Northern Asia, North America, Southern Asia (non-native), New Zealand.
Domestic ferret (Mustela furo Linnaeus, 1758) live worldwide (domesticated); New Zealand (non-native).

Eurasia .
Steppe polecat (Mustela eversmanii, Lesson, 1827) live in Southeast Europe and Northern Asia, Southern Asia.
Siberian weasel (Mustela sibirica Pallas, 1773) live in Europe and Northern Asia and Southern Asia.
European polecat (Mustela putorius Linnaeus, 1758) live in Europe, North Africa and Northern Asia.

Europe .
European mink (Mustela lutreola, (Linnaeus, 1761) live in Europe.

Mustela_range

Asia .
Mountain weasel (Mustela altaica Pallas, 1811) live in Northern and Southern Asia.
Missing-toothed pygmy weasel (Mustela aistoodonnivalis Wu & Kao, 1991) live in Shaanxi and Sichuan, China.
Yellow-bellied weasel (Mustela kathiah Hodgson, 1835) live in Southern Asia.
Japanese weasel (Mustela itatsi Temminck, 1844) live Japan and formerly Sakhalin Island, Russia.
Indonesian mountain weasel (Mustela lutreolina Robinson and Thomas, 1917) live in Southeastern Asia.
Malayan weasel (Mustela nudipes Desmarest, 1822) live in Southeastern Asia.
Back-striped weasel (Mustela strigidorsa Gray, 1855) live in Southern Asia.

North America .
Haida ermine (Mustela haidarum Preble, 1898) are also known as Haida Gwaii. They live in British Columbia, and Alexander Archipelago, Alaska.
American ermine (Mustela richardsonii Bonaparte, 1838) live in most of North America south of Alaska and the Arctic Circle; eastern Nunavut and Baffin Island.
Black-footed ferret (Mustela nigripes, Audubon and Bachman, 1851) live in North America.

Weasel Behavior and Communication

Weasel expert Carolyn King told Smithsonian, Weasels are "bold and confident out of all proportion to their size, and the do not seem to know the rules." Roger Powell, a zoologist at North Carolina State, told Smithsonian, "They're very charismatic creatures. Or maybe the word is 'enigmatic.' When you look at a weasel, what strikes you is how intelligent they are, really looking at you carefully. They're very curious, investigative creatures."

Describing a weasel in action, Richard Conniff wrote in Smithsonian, "She stood on her hind legs, brown and sleek, showing her creamy white underbelly. Her long snakelike head pivoting from side to side, frantically scanning the grass to see if she'd stirred up any movement. She leaned forward, as if to dart at something, then leaped right and left, and disappeared again, popping up a moment later, ten yards away."

Weasels sense using vision, touch, vibrations and chemicals usually detected with smell. They communicate with touch and sound and scent marks produced by special glands and placed so others can smell and taste them. According to Animal Diversity Web: Weasels rely heavily upon olfaction for intra- and interspecific communication and have been known to hunt “with nose” while searching for prey in subterranean environments. Although the sense of smell is thought to be the most important sense, weasels also use vision and hearing while hunting. Least weasels have long vibrissae (“whiskers”), which may help detect vibrations and for spatial orientation in an environment. [Source: Gina Campbell, Animal Diversity Web (ADW) |=|]

Captive weasels have been recorded making many vocalizations: barks, hisses, chirps, squeaking, squealing, and trilling. These sounds vary in response to the stimulus. Hissing is interpreted as a response to a lesser threat, while chirping is in response to a more urgent threat. Squeals are emitted when the weasel is cornered, and quieter trills are thought to be greetings between mothers and kits, and also greetings between kin. Kits are vocal, using squeaks and chirps to communicate with their mother and siblings. |=|

Weasel Dance of Death

During their "dance of death," weasels spin around, do somersaults and generally act so strange that other animals sometimes come close to investigate. In the middle of the dance, the weasel suddenly stops and lunges towards a watching animal and kills it. There have also been reports of weasels mesmerizing rabbits with their musky scents and biting the rabbits face in such a way the poor animal dies of fright.

Gina Campbell wrote in Animal Diversity Web: Weasels occasionally perform the “weasel war dance”, a colloquial term used to describe a intermittent series of leaps and twists, often accompanied by bark-like vocalizations, stiff limbs, an arched back, and erection of their dorsal and caudal hairs. There are a few hypotheses as to why this “dance” is performed, but at this time, there is no solid scientific evidence explaining this behavior. One hypothesis is that the war dance is thought to perplex prey and to give the weasel a hunting advantage, although there are cases where the weasels perform this “dance” lacking an audience. Weasels of all ages perform the dance, yet it is more common in younger individuals, especially kits playing with their siblings. [Source: Gina Campbell, Animal Diversity Web (ADW) |=|]

David Attenborough wrote : “The European stoat weighs only about a tenth as much as a rabbit. Yet it hunts them. Crouching in the long grass, it creeps close to unsuspecting victim sitting not far from its burrow. “Once within range, the stoat deliberately shows itself. It starts to dance, leaping up and down apparently chasing its own tail. It somersaults. It bounces up again and makes a back flip. The rabbit, maybe only a couple of yards or so away, is transfixed. It stops nibbling and stares with bulging eyes at this extraordinary performance. Suddenly the stoat bursts out from the grass, stabs its teeth into the back of the rabbit's neck smashing the rear end of its skull. The rabbit's legs twitch for a few moments. Then it slumps motionless. It is dead and the stoat begins the laborious business of hauling the great slack body back to its burrow." [Source: “Life of Mammals” by David Attenborough]

Weasel Hunting and Feeding

Weasels are one of the few animals that routinely kill animals much larger than themselves. Their primary prey is rodents such as rabbits, rats, voles and mice. They also eat eggs and insects. Weasels do well in agricultural areas eating mice and large insects such as grasshoppers. Weasels are efficient and often ruthless killers. Once a weasel killed 17 rats in 20 minutes. Others have been observed bringing down rabbits three times their size. They usually kill their prey with crushing bites to the head and neck.

Hunting weasels usually climb in the burrow of their prey head first and lunge at their victims, dispatching them with a jaw-locking bite to the face or the neck. Weasel's long and slender body allows them to easily enter the tunnels of rodents. This gives them an advantage over other animals such as hawks, lynx and foxes that also feed mainly on rodents. Weasels are also good tree climbers. They sometimes climb trees to get at eggs.

Weasel's live hard and die early. Their small size and high energy levels are ideal for hunting burrowing rodents but over the aeons they have made a number of evolutionary tradeoffs to reach that goal: namely a short lifespan. King told Smithsonian, "All mammals large and small average roughly the same number of heartbeats and breath in their lives—and these processes are much faster in small animals." The heartbeat of a weasel at rest is 400 to 500 times a minute.

To keep its body going a weasel must eat five to 10 meals and consume 35 percent of it body weight everyday. Weasel's can't afford to store much fat either because then they wouldn't be able to squeeze into the burrows that are so vital to hunting. Their lack of fat and slender bodies also means that weasels can’t store heat very well and also must keep eating to generate enough body heat to themselves warm.

Weasels have to eat a lot of rodents to keep going. When mice, vole and rabbit populations crash as the often do in winter weasels often don’t have enough to eat and die if starvation. The same happens if a disease hits a rodent population they rely on for food.

Weasel Mating Behavior and Young

Because weasel's have such a short lifespan they need reproduce quickly so their the species can survive. A female can give birth and raise her young in as little as three months. When rodents are plentiful she may give birth to a second litter and her offspring may give birth before fall. This mean that a single female can produce 30 offspring between spring and winter, when the population crashes.

Young females become sexually mature very quickly and mate soon after they do and are either pregnant and raising young for the remainder of their life. In one study of 500 female weasels, only two had not been impregnated. Some weasels practice delayed implantation. This means they get pregnant in the spring and delay implant as much as a year to when conditions are better for survival.

Females usually give birth to one to eight young. The number of young born and the number that survive often depends on how much there is to eat. Weasels have no permanent homes. They often occupy the burrows of their most recent victims. These hijacked burrows are also used for raising young. Usually the young are kept in them while the female hunts for food for herself and her offspring. Sometimes a male helps by catching and offering food to the young. But this male is not the father, who disappeared not long after having sex with the mother. The male who offers food reportedly does so in return for sexual favors from the mother.

Weasels and Humans

Weasels are so quick and sneaky that few people have seen them in wild. They have a reputation for raiding houses and barns. The sometimes do this but they are just as likely to kill rats, the usual henhouse thieves.

Weasels are not held in the same high regard as bunnies or even foxes. When are a person is referred to as a "thieving weasel," "gutless weasel," or "shifty weasel" the intent is usually less than flattering. In Kenneth Grahame' “Wind and the Willows”, weasels are "bloodthirsty villains" who terrorize the "poor faithful creatures" of Toad Hall.

Kevin Short wrote in the Daily Yomiuri: “Weasels are not very popular creatures. In English, to be called a weasel is definitely not a compliment. The image is sneaky and untrustworthy, with a vicious streak. My paternal grandfather, who was born in New York of Irish and Scottish stock, was obsessed with weasels, which he seemed to imagine as large dangerous animals. He often brought along a heavy "weasel-stick" with him when we went walking. [Source: Kevin Short, April 5, 2012]

Scientists used traps baited with white mice to capture weasels. Some weasels are so fond of the mice that when they are released from a trap they get caught a short while in another trap a few hundred yards a way. After they are taken they are tranquilized, weighed, and examined. Fleas and scat are collected. Radio collars unusually stay very well on a weasel's neck.

When a weasel bites a finger it is difficult to get to let go. King explained one strategy to get a weasel off: "You hold up another finger and wave it in front of the animal's face. Then, when it let's go of one finger to grab the other, you pull both finger back. Quickly."

Image Sources: Wikimedia Commons

Text Sources: Animal Diversity Web animaldiversity.org ; National Geographic, Live Science, Natural History magazine, David Attenborough books, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The New Yorker, Time, BBC, CNN, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.

Last updated May 2025