Polar bears are mostly solitary animals, and spend the majority of time hunting on their own. During the summer months, males and females mate several times to kickstart ovulation, but fertilization doesn’t occur until mid September or October. During this time, the male and female will stay together however the male can be challenged by another and so the female may mate with more than one bear. Once the egg has been fertilized the male will then leave, they do not have any role in bringing up the cubs. Pregnancy last for 2-3 months and during this time, as the winter closes in, she will dig a den in the snow to protect her and her unborn cubs. The den is just big enough for her to move around and protects her from wind, cold and predators. 2 out of every 3 births are twins (Stirling, 1978). The cubs are born soon after she enters the den, weigh only 700g (Blix et. al., 1979), where they spend the next few months drinking the mothers milk and gaining weight. In early April, the family emerge from the den and the cubs take their first steps into the world. At this point they weight about 10kg and have developed a thick layer of fur (Blix et al., 1979). They are very playful but always stick close to mum. The mother hunts for the family and cubs are able to successfully still-hunt at one year old (Stirling et al., 1978). After two and a half years of dependence on the mother (Stirling et al., 1978), the now young adults leave to venture off on their own.