Seabirds share a number of adaptations to sea life. They live longer, breed later and have fewer young than other birds. They do spend a great deal of time with their young. Most species nest in colonies. These vary from a few dozen birds to millions. Many species take long annual migrations every year, crossing the equator or circumnavigating the Earth in some cases. They feed both at the ocean's surface and below it, and even feed on each other. Seabirds vary in how much of the year they spend at sea.