Shorebirds (Charadriiformes) are a group of about 350 species of birds that include sandpipers, plovers, avocets, gulls, terns, auks, skuas, oystercatchers jacanas and phalaropes. Shorebirds, as their name implies, live along shores and coastlines. They also inhabit a variety of marine and freshwater wetlands and some members of the group—the gulls, for instance—have expanded their range to include dry inland habitats.
Most shorebirds exhibit strong flight abilities. Some species of shorebirds undertake the longest and most spectacular migrations of all birds. Arctic terns, for example, fly round-trip each year from the waters of the Antarctic where they spend the winter months to the Arctic where they breed. Other species spend long periods of time at sea. Young sooty terns, for example, leave their natal colonies and head ot to sea, where they remain for the first several years of their life before returning to land to breed for the first time.
Most shorebirds breed in large colonies and construct their nests on the ground using little nesting material or by simply scraping out a nest patch in the ground. Some shorebirds build their nests in roc crevices or ground burrows. A small number build their nests in trees. Most shorebirds lay just two to four eggs each breeding season and the eggs are often cryptically colored or patterened.
Shorebirds generally have a plummage that consists of white, gray, brown or black feathers. Many species have bright read or yellow feet. Some species also have bright red, orange or yellow bills, eyes, wattles or mouth linings.
Shorebirds feed on a variety of prey including marine worms, crustaceans and earthworms. Their feeding habits are likewise rather varied. Plovers, for example, forage by running across open ground and pecking at prey they come across. Sandpipers use their long bills to probe the mud for invertebrates. woodcock also probe for their prey but do so in their woodland habitat. Avocets and stilts swish their bills back and forth in shallow water to capture prey.
Shorebirds inhabit beaches, rocky coasts, estuaries, river banks, lakeshores and a variety of other marine and freshwater wetlands. Some species inhabit dry inland habitats while others are pelagic, spending most of their time flying over open oceans.
Shorebirds are, as a group, worldwide in distribution. There are a number of exceptions though when specific subgroups of shorebirds are considered. For example, no sandpipers breed in Australia and auks and their relatives are found only in the Northern Hemisphere. Oystercatchers are not present in Antarctica.
Shorebirds are divided into three main groups:
- Waders (or shorebirds)
- Gulls, terns and relatives
- Auks and relatives
These groups are, in turn, divided into about 17 families of birds.
The waders (also sometimes referred to as "shorebirds") include sandpipers, lapwings, snipes, plovers, stilts and various other species. Waders inhabit coasts and shorelines as well as other open habitats. There are about 220 species of waders. The waders include the largest of a the families of shorebirds—the sandpipers.
The gulls, terns and their relatives form a group of about 107 species. Other members of the group include skuas, jaegers and skimmers. Gulls, terns and their relatives are often recognizable by their long wings and webbed feet.
The auks and their relatives—the murres, guillemots and puffins—comprise a group of 23 species of birds well adapted for swimming. Auks and their relatives are often likened to diving petrels and penguins because the two groups occupy similar niches on either pole (the auks and relatives in the Arcitic and the diving petrels and penguins in the Antarctic). Yet the two groups are not closely related.