There are more than 300 species of seabirds, birds that are reliant on the sea for their food and return to the land only to nest. Some species of seabirds are sedentary. But many of them, such as most of the terns, breed in the Northern Hemisphere and migrate south during winter. All seabirds are able to feed during migration. They are adapted for covering enormous distances across oceans. Indeed, seabirds travel further than any other migrants. Like many other birds, seabirds generally migrate after their breeding season. They breed in large concentrations because of the scarcity of the land they use for nesting.
Types of Migrating Seabirds
There are two types of migrating seabirds – coastal and pelagic. They differ in their migratory patterns insofar as the distances they traverse. The former, including gannets, gulls, guillemots, cormorants and auks, remain near seashores but still cover large areas. For example, gannets that nest near the British Isles migrate along the Atlantic coasts of Europe and Northern Africa during the winter months of the Northern Hemisphere.
Pelagic, or open-sea, birds cover even greater regions. They typically have a few small nesting areas and move about across vast areas of the oceans. The most pelagic species of seabirds such as albatrosses, the largest flying seabirds; petrels; shearwaters and fulmars spend most of their lives far from land. Many of these species are truly pelagic. Even during their nesting season, they fly hundreds of miles to gather their food.
The Sooty Shearwater is one of the most populous species in North American waters. They nest on Southern Hemisphere islands along the most southern part of South America and near New Zealand from October through April, the months of summer in the Southern Hemisphere. They then migrate north for the months of the southern winter. From late spring through the northern summer, Sooty Shearwaters can be seen in large numbers off both the Atlantic and the Pacific coasts of North America. By the end of the summer, the shearwaters are again on the move, returning to the Southern Hemisphere.
There are other species of seabirds, such as Wilson’s Petrel, that share the Sooty Shearwaters’ migratory patterns. The petrels nest in the Antarctic and migrate north in April along the same routes as the shearwaters. They remain in the North Atlantic for the summer months. In the autumn, the petrels move east across the Atlantic Ocean, then along the coasts of Europe and Africa back toward the Western Hemisphere and South America. Their Atlantic Ocean loop follows the direction of the prevailing winds. They end their migration by returning to their Antarctic nesting areas. Similar flight patterns are followed by other species of seabirds that rely on the winds to carry them. Albatrosses circumnavigate the globe during their migrations.
The Arctic Tern, a very powerful bird, is also the one with the greatest endurance. It travels the largest distances of the seabirds. It migrates from its breeding grounds in the arctic climes, as far north as open land can be found, to the Antarctic regions for winter. The Arctic Tern travels a distance of approximately 25,000 miles every year, from one end of the world to the other.
Other species of seabirds also migrate across the equator, some from south to north and others from north to south. Migrations of as much as 30,000 to 40,000 miles round trip are not uncommon for seabirds. But some species travel shorter distances from their breeding grounds, depending upon the availability of food.
Most seabirds migrate with significant differences in the length of their migratory treks. The seabirds that migrate the furthest travel the greatest distances compared to other migrants.