All species › Pelicans, herons and ibises
Pelicans, herons and ibises | Pelecaniformes
Pelikaanachtigen | Pelícanos, garzas e ibis
Pelicans, herons and ibises look very different, so the order is held together mainly by molecular evidence. They are medium-sized to large birds of shallow water and wet ground, with a long neck and usually long legs; the bill differs most of all between the families and determines how food is taken — by scooping, by striking or by touch. Herons hunt by standing motionless or stalking slowly through shallow water, seizing prey with a rapid strike of the dagger-like bill rather than spearing it; an elongated sixth neck vertebra lets the neck fold into an S-shape, which makes that strike possible. They nest colonially in trees, bushes or reedbeds, and the naked chicks stay in the nest, fed by both parents.
Families in this order
- Ibises and spoonbills | Threskiornithidae4 speciesTwo bill shapes serve the same end: finding food that cannot be seen. The long, downcurved bill is pushed deep into mud or wet soil and feels for crustaceans, worms and insect larvae with a highly sensitive tip; the flat bill, widened into a spatula at the end, is swept sideways through shallow water held slightly open and snaps shut the instant something touches it. Both allow feeding in turbid water and after dark. In flight the neck is held stretched out rather than drawn back, with quick beats broken by short glides, often in single file. Breeding takes place in mixed colonies, on a platform of sticks in shrubs, trees or reeds, where both parents take turns incubating and the young reach deep into the adult's throat for food. Away from the colony these birds are quiet; within it there is grunting, croaking and the clattering of bills.
- Pelicans | Pelecanidae2 speciesThe throat pouch is not a larder but a dip net: each scoop brings in many litres of water along with the fish, and this is squeezed out along the sides, bill tipped down, before anything is swallowed. Two hunting methods occur. Swimming in shallow water, a group herds fish towards the bank in an arc or a line and then scoops in unison; or the bird drops onto a shoal from a height, turning a quarter-turn just before impact while air sacs beneath the skin absorb the blow. On the move they fly in long lines or in a V, alternating slow beats with long glides, often just above the waves where the cushion of compressed air adds lift. The chick pushes its head deep into the parent's throat to collect regurgitated food. Adults are all but silent, giving only low grunts at the colony.
- Herons, egrets and bitterns | Ardeidae14 speciesPowder-down feathers grow continuously on the breast and flanks, crumbling into a fine, water-repellent powder that the bird combs through its plumage with the comb-edged claw on its middle toe to strip off fish slime and oil. Some species in the family forage actively rather than waiting motionless: they stir the mud with one foot to flush hidden prey, or deliberately place a scrap of bread, a feather or an insect on the water's surface as bait to lure fish closer. Bitterns break sharply from the rest of the family with a solitary, well-camouflaged life in dense reed beds, where at the first sign of danger they point the bill straight up and let their streaked neck blend into the reeds. In many species the colour of the bill, legs or bare skin around the eye intensifies for a few short days at the start of courtship, then fades again once the pair has formed.