Caprimulgids
Caprimulgids
The frogmouths, oilbird, potoos, owlet-nightjars, and nightjars are about 105 unusual species of birds in five families that make up the order Caprimulgiformes. They are collectively referred to as caprimulgids. Caprimulgids have a large head, with a short but wide beak that can open with an enormous gape, fringed by long, stiff bristles. This apparatus is used by caprimulgids to catch their food of insects in flight.
Caprimulgids have long, pointed wings, and short, weak legs and feet. Most of these birds are crepuscular, meaning they are active in the dim light of dusk. Some species are nocturnal, or active during the night. Caprimulgids have soft feathers and a subdued coloration, consisting of streaky patterns of brown, gray, and black. They are well camouflaged when they are at rest, and can be very difficult to detect when roosting or sitting on a nest.
Caprimulgids may nest on the ground, in a tree cavity, or in caves. They lay one to five eggs. The chicks are downy and helpless at first, and are fed and brooded by both parents.
The oilbird
The oilbird (Steatornis caripensis ) of Trinidad and northern South America is the only species in the family Steatornithidae. This bird forages widely for its major food of oily palm nuts, and it roosts and nests in caves. The oilbird navigates inside of its pitch-black caves using echolocation, similar to bats. It rears two to four young, which are extremely fat, and at one stage of development are about 50% larger than their parents.
In the past, large numbers of fat, baby oilbirds were collected and boiled down (that is, rendered) as a source of oil for illumination and cooking. Dead young oilbirds were sometimes even impaled on a stick and used as a long-burning torch. Excessive exploitation soon threatened the oilbird, and it is now a protected species over most of its range. However, the forest habitat of oilbirds is not well protected, and deforestation represents an important threat to the species over much of its range.
Frogmouths
Frogmouths are 13 species occurring in lowland and secondary tropical forests, collectively making up the family Podargidae. Frogmouths occur from India, through Indochina, Southeast Asia, the Philippines, Australia, and many nearby Pacific Islands.
Frogmouths are rather large birds, with a body length of up to 20 in (50 cm). They have short, rounded wings and a long, pointed tail, and are relatively weak fliers. Their bill is very wide, flattened, and heavy. Unlike most caprimulgids, frogmouths do not feed aerially. Rather, these nocturnal birds pounce on their prey of invertebrates, small mammals, birds, and other small animals, on the ground and in tree branches. The cup-shaped or platform nest is usually built in a forked branch of a tree or on a horizontal branch, and depending on the species, contains one to four eggs.
The tawny frogmouth (Podargus strigoides ) occurs in Australia and Tasmania. The Papuan frog-mouth (P. papuensis ) breeds in New Guinea. The large frogmouth (Batrachostomus auritus ) occurs in lowland forests of Indochina, Sumatra, and Borneo.
Potoos
Potoos, or tree-nighthawks, are seven species of birds that comprise the family Nyctibiidae. Potoos occur in open forests from southern Mexico and the West Indies to northern Argentina and Paraguay. They have long, pointed wings and a long tail. These birds have weak legs and feet, but long claws, and they perch in an upright, almost-invisible stance on tree limbs. Potoos are solitary birds, feeding nocturnally on insects in flycatcher-fashion, by making short sallies from a prominent perch. Potoos lay a single egg on a cup-like cavity atop a broken stub of a dead branch.
The common potoo (Nyctibius griseus ) is a widespread species, occurring from southern Mexico to northern Argentina. The great potoo (N. grandis ) occurs widely in forests of Central and northern South America.
Owlet-nightjars
Owlet-nightjars (or owlet frogmouths) are seven species that make up the family Aegothelidae. These birds are Australasian, occurring in Australia, New Guinea, New Caledonia, and nearby islands. Their typical breeding habitat is open forests and brushlands.
Owlet-nightjars have long, pointed wings and a long, pointed tail. They are solitary, nocturnal animals that feed on insects in the air and on the ground. Owlet-nightjars lay their clutch of three to five eggs in tree cavities.
The Australian owlet-nightjar (Aegotheles cristatus ) occurs in savannas and open woodlands in Tasmania, Australia, and New Guinea. The gray or mountain owlet-nightjar (Aegotheles albertisi ) is widespread in mountain forests of New Guinea.
Nighthawks and nightjars
The nightjars and nighthawks are 77 species that make up the family Caprimulgidae. Nightjars are also sometimes called goatsuckers due to a mistaken folk belief that these birds suck milk from the teats of goats. Most species in this family occur in Africa and Asia, but eight species breed in North America. These birds have extremely long, pointed wings, and are excellent fliers that feed aerially on flying insects.
The whip-poor-will (Caprimulgus vociferous ) is a familiar species found in the forests of the eastern United States and southeastern Canada. Chuck-will’s-widow (C. carolinensis ) breeds in pine forests of the southeastern United States. The common poor-will (Phalaenoptilus nuttallii ) occurs in the western United States. The common nighthawk (Chordeiles minor )is a familiar species over most of the United States and southern Canada, and sometimes nests on flat, graveled roofs in cities. The lesser nighthawk (C. acutipennis ) is a smaller species of the southwestern United States. Like most species of caprimulgids, the North American species are declining because of habitat loss, and perhaps because of the effects of exposure to pesticides.
Resources
BOOKS
Bird Families of the World. Oxford: Oxford University Press, 1998.
del Hoyo, J., A. Elliott, and J. Sagatal, eds. Handbook of the Birds of the World. Vol. 5, Barn-owls to Hummingbirds. Barcelona: Lynx Edicions, 1999.
Holyoak, D.T. Nightjars and Their Allies. Oxford: Oxford University Press, 2001.
Bill Freedman