Weasels are present in Minnesota, where these small, slender predators are a common part of the state’s wildlife. They belong to the Mustelid family, a diverse group of carnivores that also includes mink, otters, and badgers. Weasels are highly adapted to hunting and surviving in the state’s varied climate and terrain. This northern environment is home to multiple weasel species.
Weasel Species Native to Minnesota
Minnesota is home to three weasel species, though their abundance varies considerably across the state. The Long-tailed Weasel (Mustela frenata) is the largest of the three and is the most widespread in North America. Males of this species can reach a total length of up to 16.7 inches.
The Short-tailed Weasel, also known as the Ermine (Mustela erminea), is the most common weasel found throughout the Great Lakes region. It is noticeably smaller than the Long-tailed Weasel, with males averaging up to 13.4 inches in total length. The smallest and least frequently encountered species is the Least Weasel (Mustela nivalis), which is considered the smallest carnivore in the world.
The Least Weasel is uncommon in Minnesota and is listed as a species of special concern in the state. This species is tiny, averaging around 7.1 inches in total length. It is significantly less abundant than the other two species, but the presence of all three gives Minnesota a complete representation of the Mustelid family.
Distinguishing Physical Features and Habitat
Identifying weasel species often relies on comparing their overall size and the relative length of their tails. The Long-tailed Weasel has a tail that is longer than half its body length. In contrast, the Short-tailed Weasel’s tail is only about a third of its body length. Both the Long-tailed and Short-tailed Weasels share a distinctive black tip on their tail, which remains dark year-round.
The Least Weasel is differentiated by its diminutive size and the complete absence of a black tip on its tail. All three species inhabit a variety of environments across Minnesota, including grasslands, woodlots, and brush piles. Their distribution follows the presence of their primary prey, which is small rodents. The Long-tailed Weasel has the widest habitat tolerance, while the Short-tailed Weasel is often found in the northern forests.
Seasonal Changes and Behavior
A notable feature of weasels in northern climates is their seasonal coat change, a process known as molting. In the summer, all three species display a coat that is brown on the back with a yellowish-white underside. As winter approaches, shorter daylight hours trigger a hormonal response, causing the weasels to molt and grow a pure white winter coat.
This camouflage, known as ermine in the fur trade, helps the weasel blend into the snowy environment, aiding in avoiding predators and ambushing prey. Weasels are hyperactive predators with an extremely high metabolism, requiring them to hunt relentlessly. They must consume a large amount of food daily, sometimes up to a third of their body weight, especially during the winter months. Their diet consists mainly of mice and voles, which they pursue even under the snow in the subnivean layer.