Weasel - A Deadly Little Carnivore
Weasels have fierce, relentless hunting techniques that make them deadly enemies of the small rodents that form the bulk of their diet and since they are strong and bold, they may also take prey larger than themselves.
The weasel is one of Britain's fiercest carnivores and is sometimes confused with a relative in the mustelid family, the stoat, but it is generally smaller. However, a male weasel and a female stoat are about equal in size.
Both species are similar in colouration, with chestnut-brown backs and white fur on the underside, but stoats have a distinct dividing line between the two colours of the coat. Weasels have an uneven margin which is different in every individual.
Weasels have long, short limbs and slender bodies, ideal for squeezing down mouse holes and mole runs and into crevices in search of prey. The head is small and bluntly pointed, with small rounded ears. Like the stoat, the weasel's tail is short and bushy and the same colour as the back, but it lacks the stoat's black tip.
Weasels inhabit mainland Britain, and on Anglesey, Skye and the Isle of Wight. Weasels do not live in Ireland. However, Irish stoats are known as 'weasels' because they are smaller than the stoats found in mainland Britain.
Weasels are quick-moving agile, relentless hunters. They patrol their territory at regular intervals, mostly at night but often running with their bodies held low or arched backs. Mice and voles pursued down into their underground runs have little chance of escape. Occasionally weasels run along the tops of walls or hedges in search of birds and their nests. They hunt mainly by scent, stopping from time to time to stand on their hind legs to test the air and survey their surroundings.
Prey is killed quickly, with a bite to the back of the head. Animals such as rabbits and large birds suffer repeated attacks on the throat and major blood vessels. Weasels eat almost any animal they can overcome and kill, from small rodents to shrews, frogs, birds, eggs, and even fish. They swim after water voles and occasionally take carrion. Weasels store excess food in or near their underground dens. Dens may contain the remains of up to 50 small rodents.
Persecution
Like all carnivores, humans have persecuted weasels and they are still regarded as vermin by gamekeepers. Weasels will steal the eggs and young of game birds and raid chicken runs, but studies have shown that the value of weasels to farmers and foresters far outweighs the harm. Moreover, a family of weasels may account for 2000 or more small rodents deaths during a year, especially mice and voles in grain stores.
During the 1950s, weasels and stoat populations declined when humans trapped rabbits commercially. But, unfortunately, weasels and stoats were often incidentally caught in gin traps and thus killed.
Competition-free Hunting For Weasels and Stoats
Weasels and stoats, with such a diversity of sizes ranging from the tiny female weasel at 23cm (9in) to the 40cm (16in) long male stoat, are thought by some ecologists to exhibit the phenomenon of 'character displacement'. They are all carnivores and, therefore, potential competitors. Still, since they are in three groups of different sizes, they can often divide up the available food resources and thus avoid too much competition. The female weasel and male stoats are specialist predators on small rodents and large prey at the two extremes of the range. The female weasel feeds almost exclusively on mice and voles, while the male stoat can kill prey up to the size of a large rabbit.
The weasel population fluctuates with the abundance of food, particularly mice and voles. Therefore, before moving to a new home, a weasel may eliminate all the rodents in that area.
Separate Territories For Male and Female Weasels
Weasels live in almost any habitat that has sufficient food and shelter. They are, of course, the most common where there are the greatest concentrations of mice and voles. However, they also live in and around farm buildings, in parkland or among stones and rubble on derelict land.
Males and females have separate territories, varying in size according to the abundance of prey. Males usually have larger territories than females and mark them with scent from musk glands beneath the tail. This scent is also released when an animal is frightened or disturbed, and, as with most members of the Mustelidae, it is very intense.
Weasels do not make regular runways within their territories, but they often use the runs and burrows of small rodents for their shelter or den and may sleep off a heavy meal in the home of a recent victim.
Weasel's Have Two Litters Of Kits
In Britain, the weasel usually has two breeding seasons a year. The first begins in March, and the young are born in April and May. The second may involve males and females reproduced during the spring season and continues until September. The seasons begin when males leave their territories to find a female in oestrus. In addition, musk glands may attract males and females to each other.
Weasel Family Groups
Unlike some mustelids, such as the stoat, weasels do not show the phenomenon of delayed implantation, and the young are born six weeks after mating. The female nurses the young for four or five weeks, and if she is disturbed during this time will move them to a new nest site. The male weasel plays no part in rearing the young.
Family groups After weaning the mother continues her parental care by teaching her offspring to hunt and kill. Their education begins when the female brings back injured and disabled prey to the nest, but she takes them on hunting excursions throughout her territory within a short time.
The young remain with their mother for up to three months by which time they can fend for themselves and their mother is involved with raising another litter. Now the young are at their most vulnerable and looking for their territories fall victim to natural enemies such as owls and hawks.
Young from the second litter often stay with their mother for longer than three months and the family may not break up until the start of the breeding season the following year. Such family groups share the same territory, but may not necessarily keep together when foraging, and individual weasels may disperse over a wide area. Occasionally, especially in winter, several family groups combine to form a pack of as many as 30 individuals.
Weasel Folklore
For centuries the weasel has been attributed with magical properties. A 12th-century bestiary says that weasel mothers can bring their dead young to life and drink the blood of their victims, a belief that probably arose from their habit of killing by a sharp bite on the neck and gripping tightly until the prey dies. They are also supposed to hypnotize their prey by 'dancing' before it. Their playful habits elicit mobbing behaviour from small birds, some of which come too close and become victims. It is unlikely that 'dancing' is a hunting technique used by many weasels, but a few may learn that it attracts prey.