There are some 9,700 species of birds alive today that inhabit a wide range of habitats including wetlands, woodlands, mountains, deserts, tundra, coasts and the open ocean. To better understand the immense diversity of birds, it is useful to examine the main groups of birds. Although there are several different ways experts classify birds into subgroups, on this website we recognize that there are 30 groups of birds:
Albatrosses and petrels, also known as tubenoses, are a group of seabirds that includes albatrosses, fulmars, prions, shearwaters, storm-petrels and diving petrels. Tubenoses are pelagic birds that spend long periods of time foraging over the open ocean. They have a widespread distribution and occur throughout most oceanic regions of the world. Tubenoses return to land only to breed. They select nesting sites on remote islands and on rugged coastal cliffs. There are 107 species of tubenoses.
Birds of prey, also known as raptors, are formidable avian predators, armed with powerful talons, hooked beaks and acute eyesight. Raptors generally have broad wings well-suited for soaring. Raptors hunt by day and feed on a variety of prey including fish, small mammals, reptiles and carrion. Raptors first appeared during the Middle Eocene. The group includes eagles, hawks, kites, falcons and old world vultures and comprises a total of 304 species.
Cassowaries and emus together form a group of large flightless birds comprised of just four species—three cassowaries and one emu. Cassowaries inhabit New Guinea and Australia, emus are restricted to New Guinea. Although their ancestors could fly, present-day cassowaries and emus have only tiny vestigial wings that are far too weak to lift their bulky bodies into the air. Their feathers have become limp and shaggy and resemble coarse fur. The two groups occupy different habitats—cassowaries prefer forests while emus opt for scrublands and grasslands.
Cranes and their relatives—the coots, rails, crakes, bustards and trumpeters—form a group that consists of 199 species. The members of this group are varied in their size and appearance, but generally have a short tail, long neck and rounded wings. The cranes are the largest birds in this group, with some species standing five feet tall. The cranes re also some of the most threatened of all bird groups. Most members of this group inhabit wetlands or lead fully aquatic lifestyles.
Cuckoos and turacos, although related and therefore grouped together, are in fact two somewhat distinct groups of birds. Both groups inhabit forests but while cuckoos have a worldwide distribution, turacos are restricted to sub-Saharan Africa. Cuckoos and turacos generally have a bulky body, small head, short beak long tail and broad wings. Cuckoos are dull colored birds but turacos have brightly colored plumage with vibrant reds and greens. There are 161 species of cuckoos and turacos.