They threaten, chase and fight other males who trespass. The strongest males father next year's pups. The bulls and cows of most seals, though, are hard to tell apart. Harbor seals are a good example of this. They do not fight over females or form breeding groups and usually mate in the water.
Female seals give birth to a single pup once a year.
Only the females care for the pups, which may be born on beaches, rocks, or even ice. Hundreds or thousands of seals may pup in the same area. It is important for a mother to clean up and listen to h er own pup when it is born. Then she can recognize its smell and squeal when she returns from a fishing trip. Pups born on the Arctic ice, like harp seals, have quite a shock at birth.