According to the American Society of Mammalogists, there are 16 weasel species in the world – 10 of them have the word “weasel” in their name.
The 3 species of weasels in Wisconsin are the least weasel, the short-tailed weasel, and the long-tailed weasel.
According to the Wisconsin Department of Natural Resources, all three may be trapped year-round with a trapping license.
Primarily nocturnal, because of their secretive nature and miniature size, weasels might be hard to spot, even in the areas where their numbers are the highest.
Here are their photos, fun facts, and a short guide on how to recognize each in case you meet them in the wild.
Note: The weasel (Mustelidae) family also includes badgers, otters, ferrets, martens, minks, and wolverines – we will just focus on “true” weasels.
Table of Contents
Weasel Species In Wisconsin
1. Least Weasel
Least weasels are the smallest weasel species and one of the smallest carnivores found in Wisconsin.
They are known under many names, including common weasels, little weasels, or simply weasels.
Quite secretive and careful, these small mammals can be very aggressive and will defend their territories from any intruder.
Identify least weasels by their long and slender bodies, short legs, long necks, and flattened heads. Notice their short tails, rounded ears, visible whiskers, and black irises; least weasels have soft fur that is brown above and white below – their tails are also brown.
When winter comes, the fur turns pure white in animals living at high altitudes and those in the northern part of their range.
- Scientific Name: Mustela nivalis
- Length: 4.5-10 in
- Tail Length: 0.5-3.4 in
- Weight: 1-8.8 oz
Unlike the other two other weasel species in Wisconsin, least weasels lack black tips on their tails, although they might possess a small number of black hairs.
They are most common in Wisconsin’s forests and woodlands with rocky slopes, marshes, brushy fields, and grasslands. Least weasels avoid dense forests and can be found throughout the state – but might be hard to detect due to their small size and shy nature.
These tiny animals are carnivores and will feed on small mammals like mice and voles, lizards, insects, birds, and bird eggs.
Fun Fact: Least weasels love to eat the heads and brains of their prey first and need to consume around half of their own body weight each day to survive.
Their small size allows them to search every hole, tunnel, or burrow in pursuit of food – they rely on their keen sense of sight, smell, and hearing when hunting.
Least weasels breed from spring to fall and have two or more litters per year with 1 to 7 young per litter. When born, young are hairless, toothless, deaf, blind, and pink – they get their teeth after 11 days and can hunt on their own by week 6.
Predators of least weasels include snakes, cats, foxes, owls, hawks, and other weasels.
2. Long-tailed Weasel
Long-tailed weasels are the largest weasel species found in Wisconsin that can be seen there statewide.
They are also known as bridled weasels, masked ermines, or big stoats and are the most widespread of any North American mustelid (carnivorous mammals like weasels, otters, fetters, minks, etc.).
Identify long-tailed weasels by their long and slender bodies, long necks, flattened heads, short legs, short and rounded ears, prominent whiskers, and black eyes. They also have dense brown fur that is white-yellow below – their brown tails have black tips and measure almost half the total body size.
During winter, in northern parts of the USA (including Wisconsin), long-tailed weasels can turn white, occasionally with yellow tints – their tails keep the black tips.
- Scientific Name: Neogale frenata
- Length: 11-22 in
- Weight: 3-9 oz
- Tail Length: 3-6 in
Short-tailed and long-tailed weasels might be difficult to tell apart, but in most parts of the state, you are more likely to see the short-tailed ones.
Long-tailed weasels are common in different habitats, including woodlands, thickets, and brushy fencerows close to the water.
These large weasels are carnivores and will take what they can get – they feed on squirrels, chipmunks, rabbits, birds, reptiles, insects, fish, and especially small rodents like mice and voles.
They breed from July to August and have one litter per year with 1-12 young. The newborns are born naked, blind, 0.1 oz heavy (similar to a size of a hummingbird), and open their eyes at around 5 weeks of age.
Fun Fact: Long-tailed weasels can delay the implantation of the embryo after fertilization and can have a pregnancy that lasts between 205 and 337 days!
They are active during the day and the night – their black eyes glow bright emerald green when caught in a spotlight at night.
Predators of long-tailed weasels include coyotes, foxes, wolves, wildcats, northern goshawks, and barred and great-horned owls.
3. Short-tailed Weasel
Short-tailed weasels are intermediate in size among these 3 Wisconsin weasels. They are the most common weasel species found in the state.
They are also known as stoat weasels, Eurasian ermines, Beringian ermines, or simply ermines.
Identify short-tailed weasels by their elongated bodies, short legs, pointed faces, very long whiskers, and long tails. They also have silky light brown fur that is white below in the summer and black-tipped tails that are around 30% of their total body length.
When the winter comes, they also turn white.
- Scientific Name: Mustela erminea
- Length: 6.7-12.8 in
- Weight: 6.3-9.1 oz
- Tail Length: 3-4.7 in
Short-tailed weasels are larger and have longer tails than least weasels but are smaller than long-tailed weasels and have shorter tails.
Short-tailed weasels are common in different habitats, ranging from wooded areas to grasslands – they prefer areas with heavy cover and avoid dense forests.
They are omnivores that feed on chipmunks, rats, rabbits, shrews, voles, insects, and frogs. Males are larger than females and tend to catch larger prey compared to females – the species might also eat some fruit and carrion when there is no prey available.
Fast and agile hunters with bodies build to enter any burrow or a narrow opening, these weasels will chase and grab prey at impressive speeds. That comes at a cost – to be that fast, weasels need to consume a lot of food.
Several studies discovered that ermines need to consume 15-37 % of their body weight per day – if there’s not enough food available or a weasel gets trapped somewhere, it may starve in a matter of days.
Short-tailed weasels breed from late spring to early summer and have one litter per year with 4-18 young.
Similar to other weasel species, short-tailed weasels can delay their pregnancy until the following spring; they are not monogamous species and will often have litters with mixed paternity.
Fun Fact: Due to their fast metabolisms and the need to constantly hunt, weasels will stockpile food if they make extra kills – this has led to their unjust reputation of being bloodthirsty animals that kill for sport!
Predators of short-tailed weasels include coyotes, foxes, goshawks, great-horned owls, and even long-tailed weasels.
Weasels VS Minks VS River Otters
Wisconsin is also home to other types of mustelids that resemble weasels: the American mink and the river otter. These creatures share a similar brown color and body shape.
One easy way to distinguish between them is by size. Among the five, the least weasel is the smallest. Long-tailed weasels are bigger than short-tailed weasels but smaller than minks; otters are the biggest and can grow more than twice the size of minks and three to five times the size of weasels!
Detecting the presence and distribution of weasels and minks in WI may pose a challenge due to their small size, swift movements, and knack for staying hidden.
Minks distinguish themselves from weasels with slightly larger sizes, a consistent dark brown hue, a streamlined body, a thick tail, small ears, and eyes. They measure 12 to 16 inches in body length without the tail and can weigh up to 4 pounds when mature.
Sometimes, minks exhibit a touch of white on their chin and throat.
- Scientific Name: Neogale vison
- Length: 12-18 in
- Weight: 1-4 lb
- Tail Length: 6-10 in
Read More: Weasel species found in Kentucky
River otters can be identified by their short legs, webbed toes, and strong, flattened tails. They range in color from light to dark brown and have 5 toes and a horseshoe-shaped heel pad.
Otters can be sometimes confused with weasels, but they are far more sizable, weighing 10 to 30 pounds, measuring 26-31 inches long, and having blunted noses and tails that are thick at the base and taper.
They can be seen around rivers, creeks, lakes, ponds, and swamps.
- Scientific Name: Lontra canadensis
- Length: 26-42 in
- Weight: 10-30 lb
- Tail Length: 12-20 in
Wisconsin is home to 3 types of weasels, the least weasel, the long-tailed weasel, and the short-tailed weasel.
All three are widespread in the state but you are most likely to see the short-tailed ones.
Unfortunately, North America’s weasel populations may be in serious decline. According to a 2019 study, their numbers have been going down and long-tailed weasels may have disappeared from large parts of their range.
You might spot them beneath short decks, porches, or other low structures, which they can use to sneak into buildings. They track the smell of mice that they’re hunting and sometimes end up indoors. One way to know they’ve been around is by their long, twisty droppings.
Weasels love to hunt and eat different animals that might cause damage to crops – that’s why many farmers and homeowners welcome these animals.
The only thing they need to look out for is unsecured chickens and rabbits, weasels might catch them too!