The ermine (Mustela erminea)

Agile and nimble predator, the Ermine finds its natural habitat in high mountains, up to 11,500 feet above sea level. Its exceptional agility and speed enable it to hunt skillfully among rocks, in trees, on snow, and even in water.

Like the variable hare and the white partridge, the ermine is also a mimetic animal. In winter, its prized fur takes on a white color, allowing it to blend in seamlessly with the snow. Only the tip of its tail, black throughout the year, betrays its presence.

Distribution and Physical Characteristics of the Ermine


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, ranging from the temperate zone to the Arctic region.

Mimicry and predators of the ermine

Similar to the rock partridge and the variable hare, the ermine also undergoes a seasonal wardrobe change. This adaptation allows the ermine to blend in with its surroundings and evade the attention of its natural predators.

During the warmer seasons, its back is cinnamon-colored with yellowish and blackish shades, while the belly appears white. In winter, on the other hand, the ermine sports a uniformly white coat except for the tip of its tail, which remains black throughout all seasons. The winter fur is extremely dense, with up to 20,000 hairs per square centimeter. This characteristic enables the ermine to effectively retain heat during the cold season.

The main predators of the ermine include the fox and raptors such as the falcon, eagle, owl, and royal owl. The grey heron is also a threat to the ermine. However, its primary enemy is human beings. Due to its prized fur, it was subjected to ruthless hunting in the past. Today, although poaching still exists, a different threat looms: landscape reclamation and fragmentation pose a far greater danger than any trap.

The Ermine

Classificazione scientifica

Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Mustelidae
Genus: Mustela
Species: M. erminea

This species is very common throughout Europe, except for Ireland and Iceland. In Italy, the species is present across the entire Alpine region, from the Karst to the Dolomites, to the Ligurian Alps.

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 weighs twice as much as the female and is at least 5 cm longer.


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-July, the gestation is much 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. The newborns are blind for about 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 birth of the young, the male continually moves in search of willing mates. Females are available even while nursing. Additionally, they can be fertilized at just three weeks of age, barely after opening their eyes.

Feeding and behavior

I mentioned that the ermine is a slender, agile, and swift predator. However, these performances come at a cost! To stay warm and in excellent shape, the ermine must consume the equivalent of 40% of its weight every day.

The animal has a carnivorous diet and primarily feeds on small rodents such as voles, but also eats birds, frogs, rabbits, reptiles, and invertebrates. Snow does not hinder its movement when hunting small mammals.

It typically kills with a bite to the neck. Once the prey is identified, the ermine approaches with great caution, and with a lightning-fast leap, seizes it at the nape to cause instantaneous death.

With this technique, the agile and deadly ermine can kill prey five times its size. The victim is either immediately consumed or carried to the den, where it becomes a food reserve. When food is scarce, the predator does not hesitate to adopt a vegetarian diet.

The ermine call

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

Where does the ermine take refuge and live?

It is a difficult animal to spot, even though it hunts during the day, it remains hidden in tall grass and among rocks. The preferred habitats for the ermine are bushy and wooded areas, high-altitude meadows, and rocky terrain. It does not favor forests with sparse undergrowth, as the populations of small mammals are not abundant.

The ermine is perfectly at home in places with a bit of ‘disorder.’ A dry stone wall, a pile of rocks, an unmown strip of grass, a stream, and perhaps even a nice hedge—what matters is the possibility of finding shelter and meadows. In meadows, it obtains food, while it gives birth to its young in the shelter of woodpiles or stone heaps.
Its den, constructed from fur, dry grass, and leaves, is almost always situated in holes, a hollow tree trunk, or the crevice of a wall.