The Cannibal Birds of the Pacific
Hordes of big black birds, about the nearest creatures imaginable to the harpies of Greek mythology, nest on desert-like South Pacific Islands. These are the vulture-like frigate birds—the Polynesian “iwas” or “thieves”—which are found by thousands in branches of the most prominent shrubs, the eight-foot-high, white flowering scaevola bushes. They are truly creatures of evil.
They carry in their feathers as parasites creatures nearly as malevolent in appearance as themselves—louse flies which look like giant, flattened black house flies. When these are shaken off they sometimes fly to small black automobiles which they mistake for their hosts.
The nests of the frigate birds are coarse, soil-cemented affairs constructed haphazardly of twigs and driftwood. During showers, the cement of this filthy building material dissolves away, allowing eggs to fall to the ground. Nesting material evidently is rare and highly prized, giving rise to theft. A bird in flight occasionally filches a loose piece from a carelessly guarded nest. The iwa will stoop to murder and cannibalism, flying off with an egg or newly hatched young to eat on the wing. There usually is one egg to a nest, entirely white and a little larger than a chicken egg.
Both sexes take turns sitting on the egg and later brooding the growing chicks. This is necessary not only to incubate the egg and keep the chick warm in cool weather, but also as protection against too intense sunshine. At the incubation time the males are resplendent with blood red, semi-transparent throat pouches blown out like balloons. These extend forward to the beak and downward to hide the breast. The color is due to innumerable blood-filled capillaries in the tissues of the pouch.
Not far from the rookeries of the iwas are those of the stupid, red-footed boobies, or gannets. The name booby is from the Spanish word “bobo”, meaning “idiot”. At times the rookeries of the aggressive marauders and the boob-victims overlap at the edges.
The frigate birds, according to a report of the Pacific Science Board, “escort the stupid, spoon-billed gannets out to feed on schools of squid and small fish. When the gannets get craws full and set sail for home to feed their young, the cruel, curve-billed iwas dive screaming after them, seize them by the tails, and sling the food out of the mouths of the smaller birds. This the iwas scoop up on the wing. This goes on from dawn to dusk. The war cries of the frigates and the plaintive screams of the fleeing gannets quiver down the trade winds like the wailings of lost souls.”
It is commonly reported that frigate birds, lacking webbed feet, never land on the surface of the water because they cannot take off again. This is not true; small flocks are frequently seen landing playfully on the Canton island lagoon, floating, and rising again seemingly without any effort whatsoever.
“The birds nesting in the scaevola,” says the report, “are tame or, depending on the point of view, too innocent or stupid to fly from their nests when approached. The explanation for this habit is their nesting from time immemorial in areas where no predatory animals, two or four legged, ever have existed. (This, by the way, is a notable characteristic of bird life in the Antarctic. The notorious skuas, with whom even the frigates could hardly compare for blood-thirstiness, will not even bother to move when men pass through a flock of them on the ice.) Tame birds were not killed off but lived to reproduce their kind. Now, unfortunately, Pacific islanders employed as laborers, occasionally club the nesting birds at night preparatory to a feast. Such vandalism and resulting pandemonium in the rookeries should be stopped by legislation.”
The ancestors of these and other kinds of sea birds have inhabited the islands during the nesting seasons for milleniums, catching fish and other sea life as food for themselves and their nestlings.