CURRENT DISCOVERY

The weasel

Size and weight vary greatly and show clear sexual dimorphism, meaning that males and females differ. In the case of the weasel, this applies to size, with males being larger and heavier than females.

• Head-torso length: 11-26 cm
• Weight: 25-250 g
• Hibernation: no
• Pups per litter: 2-10 (several litters per year)
• Mating season: Peak in spring and summer, but possible almost year-round
• Life expectancy: 1-3 years, up to 10 years in captivity

The least weasel is the smallest member of the mustelidae family. It has a very slender, elongated body with a brown back and white belly. Its legs are short with brown paws. Only a few populations, mainly those further north or in alpine regions, are white in color, similar to their relative, the ermine.

Weasels can easily be confused with stoats. However, weasels are generally smaller, or only about half the size of stoats. The dividing line between the brown back and the light-colored belly is rather jagged and not sharply defined. The paws are brown. Those animals that turn white in winter never have a black tip on their tail. A brown spot in the corner of the mouth is also typical of the weasel.

Weasels are predominantly diurnal and hunt mainly at dusk and in the late afternoon. They live as solitary animals in fixed territories, the size of which can vary greatly depending on the food supply. The boundaries of their territories are marked with scent marks and aggressively defended. Weasels are very agile and curious hunters, excellent climbers, and even swimmers. They are constantly exploring their surroundings. When hunting, they also penetrate the underground burrows and tunnels of their prey, which makes them highly successful hunters.

Weasels are found throughout Europe (except Ireland, Iceland, and the Arctic islands), in large parts of Asia, and North Africa. In North America, they are found in Alaska, Canada, and the northern United States. The species was introduced to New Zealand, where it is considered invasive and threatens mainly the populations of ground-nesting birds such as kiwis and penguins.

They prefer richly structured fallow land, fields and meadows, pastures and forest edges. They can also become very common in extensive agricultural areas and near human settlements. Weasels are extremely adaptable. They use rock crevices, hollow tree trunks or piles of stones for hunting or protection, as well as the burrows of rodents and moles. Nests are often built in abandoned vole burrows, which are then lined with leaves and hair. The animals avoid deserts, deep forests, and mountains above 3000 m.

Weasels are efficient hunters and pure carnivores whose diet consists mainly of mice. This makes them true food specialists. Their slender build enables these nimble hunters to penetrate the underground tunnels of mice. If necessary, they supplement their diet with birds, lizards, insects, worms, and even young rabbits. If the food supply is sufficient, they store it and eat it in several smaller portions throughout the day. Since weasels have a comparatively high basal metabolic rate, they need to eat about one-third of their body weight every day, which is equivalent to about five mice.

Due to their specialization in mice, weasels are bound to habitats with a minimum mouse density. They react strongly to vole gradations and follow the population fluctuations. In years with high mouse populations, there are also many more weasels; population lows are usually compensated for by several litters per year.

Natural enemies of the weasel include birds of prey, owls, foxes, and even the stoat.

The mating season for weasels begins early in the spring and lasts until late summer. However, if there is sufficient food available, the animals reproduce throughout the year and a female can give birth to two litters per year.

About five weeks after mating, 2-10 young are born in an underground nest, often built in old mouse burrows. The young are born naked, blind, and toothless. After two weeks, they eat meat for the first time, and after about two months, they begin to hunt themselves. The female is solely responsible for raising the young. During this time, she must catch a particularly large amount of prey. A litter of seven young, for example, requires 15 mice per day.

After 4-5 months, the young are sexually mature and the mother is ready to mate again. Premature young females from the first litter can then be mated themselves.

Since weasels mainly feed on animals that humans consider pests, they are usually viewed favorably. Weasels are not classified as endangered (except in Switzerland, where they have been placed on the "Red List of Threatened Species"), but in many regions they are still protected throughout the year. Only in Burgenland, Lower Austria, and Vienna are they huntable year-round; in Styria, they are considered huntable game but have a closed season from February to June.

In richly structured habitats with sufficient food supplies, weasel populations remain stable. However, the loss of natural structures, intensification of agriculture, road traffic, and domestic cats are leading to a steady decline in numbers.

The long association between humans and weasels is also evident in the various myths surrounding these animals. In England, for example, the hissing of a weasel was considered a clear sign that the person was a witch. Or the weasel itself was considered a transformed witch, which is why killing this animal would have brought great misfortune.