On closer inspection, it is clear that our female is pregnant, which is why she searches for a den site. Her choice of location will determine the disposition of the pack for most of the spring and summer. She may choose to expand a foxhole, dig a new den or simply rely on dens she has used before. She may want three alternatives so that a safe refuge will always be available. Whichever sites she chooses must be close to water, and should be situated in close proximity to a ridge that affords a clear view in all directions.
Wolves are impressive diggers.
A wolf den may extend twenty feet into a bank. During times of bearing and rearing offspring, the pack never strays far from the den. Born in early May, the pups' first visit to the outside world comes if the birth den is threatened. Then, one at a time, the mother carries the pups to a new home. On the high ground above the den site the pack waits for the pups to emerge from the den.