Least Weasel (Mustela nivalis)


Class: Mammalia
Order: Carnivora
Family:    Mustelidae
Size:    Length: 6.5 to 9 inches (17 to 23 cm)
Weight: 1 to 2.2 ounces (28 to 62 grams)
Diet: Mostly rodents such as mice and rats, but also bird’s eggs, insects and lizards
Distribution: North America, Europe, Asia, North Africa and New Zealand
Young:  3 to 10 kits, up to 3 times per year
Animal Predators:  Lynxes, foxes, hawks, owls, cats, minks, snakes and long-tailed weasels
IUCN Status: No special status
Terms: Young: Kit
Lifespan: 1 to 2 years in the wild and up to 10 years in captivity



·       In Germany, a weasel on your roof is considered a good omen.

·       Least weasels are not usually hunted or trapped because of their small size.

·       The Inuit hold the least weasel in a position of honour because of its hunting ability.

·       The scientific name mustela means “one who carries off mice,” while nivalis means “snowy,” referring to its winter colour.

·       Weasels have a resting metabolic rate 10 percent higher than other mammals of their weight.



Least weasels are the smallest weasels as well as the smallest carnivores. They are long and lean, with short legs and a flat, narrow head. Each of their feet have five toes with claws. Least weasels have chocolate brown fur with white underbellies. Their tail is relatively short, compared to other weasels. In the winter, the coats of least weasels living in northern areas turn completely white. 



Least weasels are found in North America, Europe, Asia and North Africa and they have been introduced to New Zealand as well. They are adaptive and live in a variety of habitats, including woodlands, fields, meadows, marsh edges and prairies. They make dens in the ground, within a pile of rocks or in a hollow tree. 


Feeding Habits

They mainly eat rodents—especially mice and rats, but will also eat bird’s eggs, insects and lizards. Their small size and lean body shape allow them to enter crevices and holes to pursue their prey. 



Mating season occurs year round, perhaps due to the least weasel’s short lifespan. Females and males are only found together during mating season. Just over a month later after mating, the female gives birth to a litter of tiny and helpless kits within a nest of dried leaves or fur. The babies are born blind, naked and deaf and weigh only one to two grams (0.03 to 0.06 ounces). They nurse for only three weeks before being introduced to solid food. Adult length is reached within two months and in three months the juveniles grow to full weight, with full-grown males becoming one-third larger than the females. By three to four months, the offspring disperse to go their own way. 



Weasels are known for their ferocity in bringing down prey, and even predators, larger than themselves. They have been known to attack if someone comes between them and their catch. These highly active and energetic animals have a high metabolism and need to catch a substantial amount of mice in order to provide themselves with enough nourishment. Although weasels are mainly ground dwellers, they are able to climb trees as well. They live in dens, usually taking over another animal’s home by hunting it down within its burrow and killing it. Weasels are nocturnal and sleep during the day in a den.



Least weasels are listed as Special Concern in Minnesota. 









Least Weasel Wildlife Fact File, IM Pub, US