Stoats are solitary animals and only socialise with each other in the breeding season. Mating occurs in mid-August, but the fertilised eggs within the female do not begin developing until up to 10 months later, so that the female does not give birth until the following spring. This is called delayed implantation.
Six or more, sometimes up to twelve, babies (kittens) are born in a hidden nest, often in an old rabbit burrow, lined with fur. At birth, the kittens are blind and covered in fine white hair, with a thicker patch of fur on the back of the neck to enable the mother to carry them safely in her mouth. Their eyes do not open until they are at least a month old. They are weaned at about 5 weeks and at 6 weeks old the black tip appears on their tail. After the young have left the den, the family stays together for some time, hunting and playing together. The mother defends her family fiercely.Read More: Stoats and humans