Wisconsin’s Smallest Weasel Fosters Big Connections

The following piece was written by OAS Communications Assistant Claire VanValkenburg for the Snapshot Wisconsin newsletter. To subscribe to the newsletter, visit this link. 

Shifty colleagues, dishonest enemies and slimy adversaries are often referred to as “weasels,” but is this little mammal truly worthy of such a harsh reputation?

In truth, weasels are sprightly balls of energy and elusive hunters. The least weasel is both the smallest species of weasel in Wisconsin and the smallest carnivore in the world. It evades detection so well that they have been identified as a Species with Information Needs in the Wisconsin DNR’s Wildlife Action Plan.

According to Richard Staffen, Zoologist and Conservation Biologist at the Natural Heritage Conservation (NHC), we don’t know much about least weasels because they are not sought after as a furbearer. They are captured infrequently, and their small size exhibits low commercial fur value.

“There is little population data being collected, so not much is known on how they are doing,” Staffen says.

In an effort to bolster our understanding of the least weasel, Snapshot Wisconsin and the NHC have enlisted the help of a few University of Wisconsin-Madison students to tackle a collaborative classification project.

“You’d be surprised how well weasels can camouflage into their environment!” says Elizabeth Cleaveland, who recently completed a work-study position with the Wisconsin DNR as a graduate student with the Nelson Institute for Environmental Studies.

Cleaveland worked with Staffen last year to classify roughly 400 Snapshot Wisconsin triggers categorized as weasels by citizen scientists. Cleaveland’s successor is Mace Drumright, who says that while differentiating between species can be challenging, the work is important to better understand rare species like the least weasel.

“Weasels, and mustelids in general to a degree, have a tendency to escape notice and live relatively secretive lives, so any further insight into their behaviors and habitats is useful,” says Drumright.

Of the ~400 triggers students have worked to classify, Staffen says roughly 300 triggers are identifiable enough to assign a species. The least weasel shows up most infrequently on Snapshot cameras. Cleaveland recounts feeling surprised to see a least weasel on the Snapshot Wisconsin database, noting her excitement to learn that the species was still in the state.

“There are a couple of goals tied to this project, the first one being identifying small mammals in the area and the habitats they are utilizing. This is helpful in determining if the species is still present in the area, what types of habitat(s) they are utilizing, and if any wildlife management decisions need to be addressed,” Cleaveland says.

Drumright suspects that, other than martens, the least weasel could be the least photographed Mustelid species on Snapshot Wisconsin cameras.

“Hopefully this project will give better insight into the population and how they’re interacting with their environment,” says Drumright.

Staffen and the NHC are still working on analyzing the data to determine what percentage of the population the least weasel represents compared to other Mustelidae. But he says the information gathered from Snapshot Wisconsin data can be used in conjunction with trap data from Wisconsin fur trappers and small mammal surveys to make informed decisions on the species’ status.

“I think it is one useful tool, of only a couple, to assess the current population status of these infrequently encountered or under-reported species,” Staffen says.

Staffen and the Snapshot Wisconsin team hope to expand the collaboration, moving to chipmunk and squirrels next, which is another group of triggers that are not classified to the species-level.

“I just think it is a win-win project. The students really enjoy working on the project, they learn more about identification of these animals and their biology, we get some information on status and distribution and the Snapshot project gets a more refined classification.”

Keep an eye out for our shy woodland friend. Rather than impish, consider him tactful yet discrete. However you choose to view him, here at Snapshot Wisconsin we believe that while he may be little, he is not least.