Seeking Information on the Least Weasel and Other Weasels

Weasels of Wisconsin – Long-tailed, Short-tailed, and Least
There are three small weasels in Wisconsin that get little attention and are part of the Mustelid family which includes American marten, fisher, mink, badger, skunks and otters. These three weasels look similar to each other and include the long-tailed weasel (Mustela frenata), short-tailed weasel or ermine (Mustela erminea) and the least weasel (Mustela nivalis). All three typically have a pure white coat in winter months and a brown coat in summer months. They are difficult to trap due to their small size and their fur does not have much value, meaning information on these species is rather scarce. All three species prey largely on small mammals and birds, are active year-round and den in hollow stumps, tree roots or rock piles. Below we investigate these three species a bit closer and discuss how to tell them apart.

Long-tailed Weasel - is the largest of the three weasels in Wisconsin.
o 11 – 17 inches total body length – some overlap in size w/ Ermine
o Tail is brown close to body, outer third is black (black tip present)
o Tail length is >44% of head and body length
o White coat in winter, but with black tip on tail
o Found throughout the state, but somewhat limited in the northern region

Short-tailed Weasel or Ermine – found statewide; may be more common in the north
o 9 – 13 inches total body length
o Tail is brown close to body, outer third is black (black tip present)
o Tail length is 25-40% of head and body length
o White coat in winter, but with black tip on tail

Least Weasel- the smallest of the weasels found in the state and the smallest carnivore in the world! Is a Species with Information Need because their status in the state is uncertain.
o Very small – total length (includes tail) = 6-8 inches; not much larger than their small mammals prey
o Never has a dark black tip on tail
o Tail is always <25% of head and body length
o May have 2-3 litters/year; active day and night
o Found in grasslands, pastures, old fields and woodlots throughout much of the state, but most common in the southern half.

We are very interested in learning more about these weasels and hope you can contribute information if you see them!

Posted on October 2, 2023 03:50 PM by rstaffen