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 Michigan are the short-tailed weasel, the long-tailed weasel, and the least weasel. They can be found throughout the state.
Despite sharing many similarities, these three species also have several key differences.
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.
3 Weasel Species In Michigan
1. Least Weasel
Least weasels are the smallest weasel species and the smallest carnivores found in Michigan.
They are known under many names, including common weasels, little weasels, or just weasels.
Quite secretive and careful, these small mammals can be very aggressive. Identify least weasels by their long and slender bodies, short legs, long necks, and flattened heads.
They also have 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 the 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
Least weasels resemble long-tailed weasels but are a lot smaller and have shorter tails that do not have black tips.
They are most common in Michigan’s forests and woodlands with rocky slopes, marshes, brushy fields, and grasslands – they avoid dense forests.
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 head and brains of their prey first and need to consume around half of their 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.
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 one of the largest weasel species found in Michigan.
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 Michigan), 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
Long-tailed weasels resemble short-tailed weasels but lack a white line on the inside of their legs.
Long-tailed weasels are common in different habitats, including woodlands, thickets, and brushy fencerows close to water.
They 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.
These large weasels 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 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 the coyotes, foxes, wolves, wildcats, northern goshawks, and barred and great-horned owls.
3. Short-tailed Weasel
Short-tailed weasels are intermediate in size among 3 Michigan’s weasels.
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; when the winter comes, it turns white and the tail that keeps a black tip year-round is around 30% of the total body length.
- 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 while they 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 than 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.
Summary
Michigan is home to 3 types of weasels, the least weasel, the long-tailed weasel, and the short-tailed weasel.
Any of these can be seen both in the Upper or Lower Peninsula, mostly in wooded or rocky areas without dense trees, around crop fields and small wooded areas.
These animals typically den in hollow logs, rock piles, or abandoned buildings like barns.
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!
Read More: Weasel species found in Ohio