Weasel facts

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Weasel and young rat @ Nga Manu Images

Weasel and young rat @ Nga Manu Images

Weasels are mustelids. That means they belong to the same animal family as stoats and ferrets. Weasels are the smallest of the mustelid family. They have red/brown coats with white fur on their belly and short tails. Adult weasels are about 20cm to 25cm long.

Weasels have a long, thin body with short legs. They are hunters and are small enough to follow a mouse into its tunnel. Mice are their favourite food but they also hunt birds, eggs, insects and lizards when they can’t find mice. They can kill an animal as big as a rabbit and carry it back to their den.

Weasels are the world’s smallest carnivores.

Weasels often take over the nests of their victim to make their own den. They also make dens among tree roots. They line their dens with grass and fur. Weasels may have several dens in their territory where they can rest and be safe.

Weasels can kill animals much bigger than themselves. Their teeth are small but very sharp. They kill their victim with a single bite to the back of the neck.
Weasel with mice @ Nga Manu Images

Weasel with mice @ Nga Manu Images

Female weasels are much smaller than males. A female weasel can weigh up to 80g, but a male weighs up to 150g – so males are almost twice as big as females.

Female weasels give birth to 4-6 young. Baby weasels are deaf and blind and do not have fur when they are born. They grow very quickly and are good hunters by the time they are 8 weeks old.

A mother weasel and her young hunt together in a gang until the young are about 9-12 weeks old. The family then breaks up and the young leave to find their own territories. Adult weasels live alone. A weasel can live for about 3 years but many die before this.

The weasel’s long thin body shape means it loses a lot of body heat. Weasels must eat a third of their body weight every day so that they have enough energy to survive.

Weasels like to live in gardens, farmland and scrub – probably because these are places where mice live. Weasels are not as common in New Zealand as their cousins, stoats and ferrets. There are no weasels on Stewart Island.

Weasels were first introduced to New Zealand in 1885. 67 weasels were released by Lake Wanaka in the South Island.

What’s useful about weasels?

Weasel with mouse @Nga Manu Images

Weasel with mouse @Nga Manu Images

They eat mice – lots of mice!

What’s the problem with weasels?

Weasels also eat birds, eggs, insects and lizards – especially when there aren’t any mice for them to eat. They eat New Zealand’s native weta. Studies of the weasel’s diet show that weasels probably eat lizards more often than stoats do. Luckily weasels aren’t as common in New Zealand as stoats are.

People used to believe that weasels had magical powers and could bring their dead young back to life. They also believed that weasels hypnotised their victims by dancing. Dancing is now thought to be something weasels do when they have internal parasites making them uncomfortable.