Baikal seals are slightly polygamous and slightly territorial, although not particularly defensive of their territory. Males mate with around three females if given the chance. They then mark the female's den with a strong, musky odor, which can be smelled by another male if he approaches. The female raises the pups on her own; she digs them a fairly large den under the ice, up to 5 m (16 ft) in length, and more than 2 m (6 ft) wide. Pups as young as two days old then further expand this den by digging a maze of tunnels around the den. Since the pup avoids breaking the surface with these tunnels, this activity is thought to be mainly for exercise, to keep warm until they have built up an insulating layer of blubber.
baikal seals are slightly polygamous and slightly territorial although not particularly defensive of their territory males mate with around three females if given the chance they then mark the female's den with a strong musky odor which can be smelled by another male if he approaches the female raises the pups on her own; she digs them a fairly large den under the ice up to 5 m (16 ft) in length and more than 2 m (6 ft) wide pups as young as two days old then further expand this den by digging a maze of tunnels around the den since the pup avoids breaking the surface with these tunnels this activity is thought to be mainly for exercise to keep warm until they have built up an insulating layer of blubber