In spring the alpha female has her puppies after a period of about 63 days. She has pups in a den (which could be a rock cave, crevice or a hole in the ground.) Other wolves have their pups on the ground, without any shelter. The dens are usually near water. The pups leave the den when they are 4 weeks old. At this age they spend a lot of time outside the den, but run back in if they hear a startling noise. When the mother goes hunting an older sibling "baby-sits". As the pups get older they eat more food. Adult wolves carry their pups around so they are used to the territory they live in. At about 8 weeks of age wolf pups begin growing adult fur. At about midsummer time the pups begin traveling as a part of the pack. At this time they get ranks.