As It Happens

Less snow means Poland's white weasels could face extinction, says scientist

A new study has found that least weasels, which turn white in the winter to camouflage, are struggling to hide from predators because of less and less snow.

The weasels roamed the Bialowieza Forest undetected by their predators by turning white in the winter

Less snow in Poland's Bialowieza Forest means that the least weasel, which turns white in the winter to camouflage itself, is at risk of local extinction. (Karol Zub)

The white weasels of Poland's Bialowieza Forest could soon face extinction in the area, and scientists believe climate change is to blame. 

A new study has found that a lack of snow in the area is causing a subspecies of least weasels, which turn white in the winter, to be unable to camouflage their fur and hide from wolves and other predators. 

The findings were recently published in the journal Scientific Reports

Kamal Atmeh, co-author of the study and a PhD student at France's Claude Bernard University, spoke with As It Happens host Carol Off about the fate of the weasel.

Here is part of that conversation. 

Mr. Atmeh, first of all, can you just describe these weasels?

Yeah, actually in the Bialowieza Forest, we have two subspecies of weasels. One turns into white during the winter and the second stays brown all year long and is also a bit bigger than the other subspecies.

A least weasel in its brown summer coat. (Karol Zub)

How are they becoming more endangered because of the fact that they are white in the winter?

We actually analyzed ... climatic data going back from 1967 until 2017. We noticed that over the 50 years, there has been a significant decrease in snow cover in the region.

During the same period, when we captured weasels in the Bialowieza Forest, we found that ... when there was less snow cover in the winter, the white weasels was significantly reduced in population during summer and autumn.

This was a response to the environmental conditions during winter. We can analyze this as some sort of predation due to their camouflage.

You did this study over about 15 years. What did you do in order to test your idea that these white-coated weasels were being subjected to predators?

We took two stuffed toys — we had one brown model and one white model — which we exposed against contrasting backgrounds, which were a snow layer and bare ground, such as grass.

Then we observed how the predators would react to each model based on if they were well-camouflaged or not.

For example, we wanted to see if the predators would detect the brown models when they were on snow, or the white model when they were on the ground.

What we found is that predators detected the model significantly when they were incompatibly camouflaged and this supported our result that this lack of camouflage is causing the decrease in the weasel population.

Poland's least weasel on its last phase of moult.

How many stuffed toys [did you] lose in the course of this research?

We lost quite a lot.

But we managed to get 138 model predator encounters. And we had a 31.9 per cent rate of detection, which was actually pretty well.

But, yeah, sometimes they really love the toys. 

Some foxes would dig the toys when they are not well-camouflaged.

A red fox sniffs a toy model of a least weasel as part of the study. (Karol Zub)

The brown weasels that don't turn white, they were exposed to predators in the winter as well. How did they protect themselves from predation?

Actually, when there is a lot of snow, predation is not much of a problem because the weasels can hide under the snow and escape predators.

They also hide in the snow because that's where they can find food, which are rodents. That's why when there is a layer of snow, this is not the problem.

What do you think is going to happen to the white-coated weasels of Poland?

If they are not able to adapt to these changing environmental conditions, they might face local extinction.

I think what we should do is to continue monitoring them to see if they're expanding to the northern hemisphere or more to the east where the environmental condition and snow covers are still lasting a bit longer.

Written by Earvin Solitario. Interview produced by Samantha Lui. Q&A has been edited for length and clarity.