A seabird is any bird that spends most of its time at sea and depends on the sea and its islands for all its basic needs. The sea provides food, and its remote islands and rocky outcroppings provide safe nesting and resting places. For 60 million years, these highly specialized and diverse birds have adapted to life on the world’s vast oceans. Only about 260 of the world’s 8,600 or so species of bird are called seabirds.
One particularly skilled seabird can’t even swim. The frigatebird can only fly and perch, but its acrobatics in the air win it all the food it wants. It is an aerial pirate, chasing, attacking, and stealing food from other birds. Skimmers pick up food as they skim low over the surface of the water. Some divers, like puffins, beat their wings up and down underwater to chase after fish. Brown pelicans plunge-dive, which means they spot fish from the air and drop straight down in a single motion to catch it.
Most seabirds eat fish, but squid is also a popular food. A puffin can hold as many as 60 little fish in its mouth at once! A pelican might scoop up as much as two gallons of water along with its fish catch, but it will swallow as little of that water as possible. Gulls like to eat clams and other shellfish. A bird called the little auk scoops up tiny animals called zooplankton that float through the ocean.
Most seabirds have a small patch of skin called a brood patch on the lower part of their bellies. They use this patch like a blanket to keep their eggs warm until they hatch. Puffins carve out tunnels for their nests underground. Other seabirds use twigs, rocks, or seaweed to build nests. Still others have no nests at all. They lay their eggs on a bare rock ledge, a tree branch, or in a shallow scrape of sand. Murre chicks, when they are 18 to 25 days old and still unable to fly, make spectacular dives from their cliff nests to the ocean below, where adult murres will care for them for many weeks.
Seabirds, of course, live on or near the oceans. They live in polar waters, equatorial waters, areas of cold water currents, upwellings, and other places where the water is turbulent and the food is abundant. Fish feed in these areas because the turbulence, or motion of the water, stirs the nutritive brew that promotes a rich growth of plankton. Fish feed on plankton, and seabirds eat a lot of fish.
Many seabirds exist today in thriving populations. Some have been protected for hundreds of years—as in Northern Europe, where as long ago as the 17th century some societies and cultures carefully managed their use of seabirds to maintain sizable populations. There is still danger from oil pollution, and from humans and their introduced animals invading seabird colonies for eggs, but the future for most seabirds, for now, seems secure.