Todas as espécies › Gannets and cormorants

Gannets and cormorants | Suliformes

Genten en aalscholvers | Gannets and cormorants | Alcatraces y cormoranes

Gannets, cormorants, darters and frigatebirds: birds that take their food by diving or plunging after it. All four toes are joined by webbing — the hind toe is turned forward to take part — and the external nostrils are grown shut, so the bird breathes through its mouth and ships no water on entry. The throat skin is bare and stretchable, letting a large fish go down whole, and glands above the eyes get rid of the sea salt that comes in with it. They breed in dense colonies and have no brood patch: the eggs are kept warm under the blood-rich webs of the feet, and the young hatch naked and helpless and stay a long time at the nest. On the west coast the colonies depend entirely on the sardine and anchovy shoals fed by the cold upwelling there, and their numbers track the movements of that fish.

Famílias desta ordem

  • Frigatebirds | Fregatidae2 espéciesA family of five tropical seabirds, two of which occur in the area of this guide. Magnificent Frigatebird is common along the Pacific coast and breeds in colonies on islands and in mangroves, for instance on Isla de la Plata off Ecuador and in the Galápagos; Great Frigatebird breeds in the Galápagos, where both species nest side by side, and is scarce along the mainland coast. Frigatebirds have the largest wing area relative to body weight of any bird: long, narrow, angled wings and a deeply forked tail. On rising air they climb high and glide over long distances, sometimes for weeks without landing. The plumage is not waterproof and the legs are short and weak, so they cannot swim or take off from the water. They snatch flying fish and squid from the surface in flight and chase boobies, terns and gulls until these drop their catch. In the colony males inflate a bright red throat pouch and quiver their spread wings to attract females flying over. The single chick fledges only after five or six months and is then fed by the parents for a long time, so that many birds breed only every other year.
  • Boobies and gannets | Sulidae6 espéciesLarge seabirds with a cigar-shaped body, long pointed wings and a wedge-shaped tail; the heavy conical bill has no hook, but its finely serrated cutting edges hold a slippery fish. The eyes are set well forward and give the depth judgement the plunge dive demands: from a great height the bird falls into the sea with its wings swept back, air sacs under the skin of head, neck and breast absorbing the impact. This guide covers six species, all of the genus Sula. Over the cold Humboldt Current along the coast of Peru the Peruvian Booby hunts shoals of anchovy in dense swarms, alongside sea lions, dolphins and shearwaters, and breeds in colonies of tens of thousands of pairs on the guano islands and rocky coasts. On the Galápagos and other offshore islands the Blue-footed and Nazca Boobies nest on the ground and the Red-footed Booby in shrubs and trees, while the Brown Booby occurs mainly along the tropical coast of Colombia and Ecuador. The chick hatches almost naked and takes several years to reach adult plumage.
  • Anhinga and darters | Anhingidae1 espécieA small family of four species of tropical and subtropical fresh waters. In the region covered by this guide only the Anhinga occurs, in the lowlands on both sides of the Andes, in marshes, rivers, oxbow lakes, lagoons and mangroves. It resembles a cormorant with a slimmer body, a long, fan-shaped tail and a very long, thin neck; the male is black with silvery-white markings on the wings, the female has a pale brown head, neck and breast. A special hinge between the eighth and ninth neck vertebrae lets the bent neck shoot forward like a spring, and with its straight, dagger-sharp bill the bird spears a fish underwater, then shakes it free at the surface, tosses it and swallows it head first. It often swims low in the water, with only the snaking head and neck showing. Because the feathers let water in, after hunting it must sit on a branch for a long time with wings spread to dry and warm up. In flight it alternates flapping with gliding, and on thermals it circles high like a small raptor. Anhingas nest in trees over water, often among cormorants and herons.
  • Cormorants and shags | Phalacrocoracidae4 espéciesLong-bodied dark waterbirds with a long neck and a bill sharply hooked at the tip: the fish is gripped, not speared. They dive from the surface and swim under water with both feet at once; the legs are set far back, which makes walking laboured, and the stiff wedge of a tail works as a rudder. The plumage lets itself be partly soaked, which cuts buoyancy but obliges the bird to dry off after fishing with its wings half spread — the posture the whole family is known by. Even the Flightless Cormorant of the Galápagos, whose wings have shrunk to stubs, still holds them out in this way to dry. The nest of sticks, weed or guano stands in a colony on rock, in trees or in reedbeds; along the Humboldt Current the Guanay Cormorant breeds in huge colonies on the guano islands. Two to four pale blue eggs under a chalky coating, and naked young that put on black down within days.