Stoat (Mustela erminea) in the Dolomites

The stoat

The stoat (also known as the ermine, especially in its winter coat) is a small, agile predator that lives in high mountain environments, reaching elevations of up to 3,500 metres. Its speed and agility allow it to hunt with ease among rocks, across snow, and even in water.

Like the mountain hare and the rock ptarmigan, the stoat is perfectly adapted to its alpine environment. In winter, when its coat turns completely white, the stoat—often referred to as an ermine—blends almost seamlessly into the snow. Only the black tip of its tail gives it away.

Distribution and physical characteristics of the ermine

Distribution

In Italy, the ermine is present with a fragmented distribution only in the Alpine region. Globally, this small predator has a wide distribution across the entire Northern Hemisphere, from North America to Europe and Asia, spanning the temperate zone to the Arctic region.

Where to find the stoat in the Dolomites

In the Dolomites, the stoat lives mainly in open high-altitude environments, where the forest begins to thin out and gives way to alpine meadows, rocky areas, and low shrubs.

It can generally be found between 1,500 and 2,300 metres, in that transition zone where woodland gradually opens into more exposed terrain. In the Dolomites, it is rarely seen much higher, where the landscape becomes too rocky and offers fewer resources.

The stoat prefers environments rich in hiding places: piles of stones, dry stone walls, fallen logs, shrubs, and forest edges. It tends to avoid dense, “clean” forests, where the understory is limited and prey is less abundant.

It is closely linked to areas with a good population of small rodents, such as voles. For this reason, it is often found in alpine meadows and in transition zones between woodland and open ground.

In winter, it becomes even harder to spot. Its white coat makes it almost invisible against the snow, and often the only sign of its presence is a sudden movement among the rocks or the distinctive black tip of its tail.

Like many mountain animals, the stoat avoids heavily frequented areas. To have a chance of seeing one, it’s best to move during the quieter hours of the day and in less disturbed environments.

Camouflage and predators of the ermine

Like the rock ptarmigan and the mountain hare, the stoat changes its coat with the seasons. This adaptation allows it to blend into its surroundings and avoid the attention of predators.

In summer, its coat is brown on the back with lighter underparts. In winter, it turns completely white, except for the tip of the tail, which remains black all year round. The winter coat is extremely dense — up to 20,000 hairs per square centimetre — allowing it to retain heat even in very cold conditions. This pure white fur was once highly prized and widely used for royal garments, which led to centuries of hunting.

The stoat’s main predators include foxes and birds of prey such as eagles and owls, including the eagle owl.
The grey heron can also prey on the stoat. However, its main threat comes from humans. In the past, it was widely hunted for its valuable fur. Today, although poaching still occurs, the real danger is habitat loss and fragmentation.

Dimensions and weight of the ermine

The slender and elongated body of this small predator measures between 20 cm and 32 cm. The length of the ermine’s tail ranges from 8 to 12 cm. The weight varies from 100 to 400 grams, with an average weight of 300 grams. The male is twice as heavy as the female and at least 5 cm longer.

Reproduction

The male ermine is polygamous and thus accepts multiple females within its territory. The mating season can occur both in spring and summer. If mating occurs in spring, the gestation period lasts about two months. If mating occurs in June or July, the gestation period is significantly longer, lasting 8-12 months. However, gestation pauses during unfavorable months, and only as spring approaches does the embryo resume development within the mother’s uterus. This allows adjusting the birth dates to the best environmental conditions for the offspring’s development.

At the end of pregnancy, 4-6 offspring are born. Newborns are blind for approximately 6 weeks and are nursed for 7 weeks. In years with abundant food, up to 14 offspring can be born. However, this increase in the ermine population is short-lived: at least half of the young die during the first winter. The average lifespan of an ermine in the wild is only 1-2 years.

During the mating season, the male continually moves in search of willing mates. Females are available even while nursing. Additionally, they can be fertilized as early as three weeks of age, barely after opening their eyes.

Diet and behaviour

To keep up this pace, a stoat needs to eat around 40% of its body weight each day. It feeds mainly on small rodents, such as voles, but will also take birds, frogs, reptiles, and insects.

The ermine call

The ermine produces sounds resembling sharp trills and chirps of a bit of bird, often used during courtship and communication with other ermines.

The stoat’s trill

Where does the ermine take refuge and live?

The stoat is a difficult animal to spot. Even though it is active during the day, it tends to stay hidden in tall grass, among rocks, and in dense vegetation.
It prefers varied habitats such as shrub-covered areas, forest edges, alpine meadows, and rocky terrain. It tends to avoid dense, “clean” forests, where the understory is limited and prey is less abundant.

The stoat thrives in places with a certain degree of “disorder”. Dry stone walls, piles of rocks, unmown grass, streams, and hedges all provide ideal conditions. What matters is the availability of both shelter and hunting grounds.
It hunts mainly in open areas, while it raises its young in sheltered spots such as woodpiles or stone heaps. Its den, lined with fur, dry grass, and leaves, is usually located in burrows, hollow tree trunks, or crevices in walls and rocks.

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Scientific classification of the ermine

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