Gannets and cormorants | Suliformes

Families in this order

• Frigatebirds | Fregatidae2 speciesThe plumage is barely water-repellent and the feet are far too small to swim with or to take off from water, so everything has to happen in the air. Flying fish and squid are snatched from the surface in a low sweep without the bird getting wet, and other seabirds are chased and pulled by tail or wing until they let go of their catch, which is caught as it falls. A very large wing area on a light body lets them soar on thermals for days on end and sleep on the wing far out at sea. The nest is a loose platform of sticks in a low shrub on an island, where the male inflates a bright red throat pouch into a balloon for weeks at a time and accompanies it, wings spread wide, with a rattling drumming. A single chick is raised, dependent for so long that a pair does not breed every year.
• Boobies and gannets | Sulidae7 speciesThese seabirds hunt by folding the wings half back and dropping into the sea from a great height like an arrow; just before impact the wings close flat against the body, and the bird may swim on after the fish for several metres more. Air sacs under the skin of the neck and breast absorb the blow, the nostrils are sealed shut — breathing goes through the corners of the gape — and forward-facing eyes give the depth perception needed to judge a shoal. There is no brood patch: the egg is kept warm beneath the blood-rich webs of the feet, which the bird stands on. Nests lie in dense colonies on cliff ledges or flat islands, a heap of seaweed and droppings that the pair reaffirms at every return with an elaborate greeting of fencing bills and pointing skyward. At sea they are silent; in the colony a harsh, grating croaking carries on day and night.
• Anhinga and darters | Anhingidae1 speciesThe bill is straight and tapers to a sharp point, without a hook: the fish is not gripped but speared. Several neck vertebrae are set at a fixed kink with a sling of muscle that works like a loaded spring, so the head shoots forward in a sudden thrust. The plumage soaks through and the bones are heavy, so the bird swims low and slowly, often with only the thin, winding neck above water while the body stays out of sight. The tail is long, broad and fan-shaped, with cross-ribbing on the outer feathers; it serves as a rudder underwater and as a lifting surface in the air, for in the warm hours these birds circle high on thermals with the tail spread instead of travelling low over the water on steady wingbeats. They live on fresh, still or slow-flowing water with plenty of vegetation, not at sea. Male and female differ in colour. The nest is a stick platform in a tree over water, often among nesting herons and ibises; there a fast rattling clatter is heard, but away from the colony the bird is silent.
• Cormorants and shags | Phalacrocoracidae6 speciesTo swallow a caught fish whole, the cormorant first tosses it into the air with a flick of the head and catches it again so it slides down head-first rather than sideways. Through the bare skin of the throat, which acts as a cooling system, the birds shed excess heat on hot days by fluttering that skin rapidly, a mechanism also used by herons and pelicans but especially visible in cormorants because the throat patch is left bare. Shortly before and during the breeding season some species grow temporary ornamental plumes on the head or body that disappear again once mating is over, and within the colony nest material is often stolen from an unguarded neighbouring nest rather than gathered fresh. The eggs have a thin, rough, chalky outer layer over a pale blue-green shell that is often soiled and discoloured within a few days of incubation.