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Least Weasel


Despite being the smallest predatory mammal in the world, the least weasel is a fearless predator, capable of killing a hare 5-10 times its weight. Least weasel is specialized in preying on small rodents, especially moles from their underground tunnels. Small birds, eggs and invertebrates are also an option.


In Finland least weasels are protected and considered least concern. They inhabit the whole country. Vegetated forests are the preferred habitat, but sometimes it also settles in a farming environment. An abundant rodent population attracts weasels to the area. The weasel uses several underground nests made by other animals. The nests are lined with the hair of prey animals.


Least weasels’ closest relative is a stoat. Least weasel and stoat can best be distinguished by the tip of the tail, which on a stoat is always black. Least weasels’ tail is always the same color as the rest of the body. Both have white winter coat. In the summer the coats are brown on the back and white on the stomach. The least weasel is also smaller than a stoat and has a shorter tail.

Least Weasel

Mustela nivalis

Class: Mammalia – Mammals

Order: Carnivora – Predatory animals

Family: Mustelidae – Martens

Size: 35–120 g, length 14–24 cm + tail 3–5 cm, male larger than female.

PROPAGATION: Gestation period 34-37 days. Cubs are usually born in April-June. In a good mole year, another litter in late summer. 1-15 offspring at a time (typically 4-6). Becomes independent at 3-4 weeks of age, sexually mature at 3-4 months of age.

Did you know…

The least weasel does not hibernate but spends a large part of the winter hiding under the snow, hidden from the predators. Lots of least weasel tracks on the snow can indicate a small mole population.