Stoats and weasels are very closely related, belonging to the same genus, Mustela. This can make it tricky to tell them apart in camera trap images. Thankfully, there are a few defining features that can be used to distinguish between them.
The most obvious difference in appearance between the two is the black, bushy tip at the end of a stoat’s tail. Comparatively, the tail of a weasel is short, stubby and entirely orange-brown.
However, if the tail isn’t visible, there are other subtle differences that can be used to tell these small mammals apart. Stoats are typically larger than weasels, measuring about 30-40cm, whereas weasels have a whole body length of 20-27cm. In addition, stoats run with bounding movements, characterised by an arched back. Weasels, however, move more quickly with their back flat.
If you happen to spot one of these animals in winter, you may notice that the coat is completely white. Weasels remain orange-brown all year round, so if this is the case, you have definitely spotted a stoat. However, stoats’ fur doesn’t always change colour, in which case you can use the clues above to identify which mustelid you’re looking at.