NIGHTJARS: CaprimulgidaeWHIP-POOR-WILL (Caprimulgus vociferus): SPECIES ACCOUNTS
GRAY NIGHTJAR (Caprimulgus indicus): SPECIES ACCOUNTS
The Caprimulgidae family is the largest family in the order Caprimulgiformes. Nightjars measure 6 to 16 inches (15 to 40 centimeters) from head to tail. Their weight ranges from 0.7 to 6.6 ounces (20 to 188 grams). Plumage (feather) color includes brown, gray, brownish yellow, and rufous (reddish brown). Those colors form patterns that help nightjars hide in trees.
The nightjar has a large head with large eyes that provide the strong vision needed to see during the night. The bird's small bill opens to reveal a large gape, which is the width of the mouth when open. Nightjars have short legs and long wings and tails.
Nighthawks, a group of nightjars, don't have bristles, and they usually have longer tails and wings than nightjars.
Nightjar species are found throughout most of the world. No species live in the Arctic, Antarctic, and some oceanic islands.
Some nightjar species migrate across continents. These include European nightjars that breed in Europe and spend the winter in Africa.
Nightjars live in habitats ranging from semi-arid deserts to rainforests, where abundant rainfall produces plentiful growth. The birds occur in deciduous forests where trees shed leaves and coniferous forests that do not undergo seasonal changes. Nightjars also live in grassland areas with fewer trees.
Nightjars fly after prey or hunt on the ground for food such as insects, flies, beetles, ants, and caterpillars. Birds sometimes eat spiders. Larger nightjars may eat frogs and small birds.
BEHAVIOR AND REPRODUCTION
Nightjars spend the daytime roosting, sitting quietly in trees. Many species are nocturnal, meaning that they are active at night. Some species are crepuscular (kri-PUS-kyuh-lur), starting their activities at twilight, the time between sunset and darkness. During active times, nightjars hunt for food, eat, and mate. Nightjars are noisy at night. Males sometimes call to attract females, while other calls are territorial songs to warn other birds to stay away from a location.
The start of the breeding season depends on when there is a large amount of insects to feed young birds. In most climates, there are fewer insects during winter months, so breeding takes place in the spring or summer. Females of some species breed twice during the season and have two broods (sets of young).
Most nightjar species are monogamous (muh-NAH-guh-mus). Some species mate for life. In other species, male and female stay together for the breeding season.
Nightjars do not build nests. Females lay one to two eggs on the ground or in a tree branch. They incubate the eggs, sitting on them to keep them warm. Males of some species also help with incubation. Eggs hatch in seventeen to twenty-one days, and in some species, both parents feed chicks. The young fledge, grow feathers, in about two weeks. Two weeks later, the birds are able to fly and feed themselves.
Nightjars are hunted by predators including owls, crows, hawks, foxes, rats, and snakes. To make it difficult for predators to see them, the birds take advantage of their coloration and remain motionless, perched in trees, during the daytime.
WHY BIRDS HAVE WHISKERS
Many nightjars have whisker-like bristles around their mouths, but opinion is divided about why the birds have bristles. Some researchers think that the bristles help the birds capture prey while flying by helping to push insects into nightjars' mouths. Others disagree with that explanation, saying the bristles may protect the nightjars' eyes from being injured by prey struggling to escape.
NIGHTJARS AND PEOPLE
Nightjars received their name because their loud night call jarred (disturbed) sleeping people. The birds are also known as "goatsuckers" because people wrongly thought the birds drank milk from goats and cows. Nightjars actually hunt insects near the animals.
Several nightjar species are at risk as their habitat is lost when trees are cut down, according to World Conservation Union (IUCN). The Puerto Rican nightjar is Critically Endangered, facing an extremely high risk of extinction, dying out. That ranking could be changed to Endangered, facing a very high risk of extinction, due to conservation programs.
The white-winged nightjar's status has changed from Critically Endangered to Endangered, reflecting the new discovery of birds in Paraguay. Also Endangered is the Itombwe nightjar. Just one bird has been found in the Democratic Republic of the Congo.
Rated Vulnerable, facing a high risk of extinction, are the satanic-eared nightjar and Bonaparte's nightjar.
Physical characteristics: Whip-poor-wills range in length from 9 to 10 inches (23 to 26 centimeters). They weigh from 1.5 to 2.4 ounces (42 to 69 grams). Their patterned plumage is brown, gray, and, white.
These birds have rounded wings. Their feet are so tiny that whip-poor-wills perch on trees length-wise, as if lying on their sides.
The whip-poor-will is named for its call. People thought they heard the bird, say, "whip-poor-will." Birds make this call as the sky becomes dark at night and just before dawn when skies lighten. Whip-poor-wills also call their name at night, especially when the moon is visible.
Geographic range: Whip-poor-wills live in the United States, Canada, Mexico, Cuba, and Central American countries including Honduras.
Habitat: Whip-poor-wills live in pine forests, deciduous forests, and open land where there are fewer trees.
Diet: Whip-poor-wills eat moths, beetles, ants, grasshoppers, and other insects.
Behavior and reproduction: Whip-poor-wills are nocturnal. Their breeding season starts at the beginning of May. Birds mate in areas ranging from Canada to Mexico, and then migrate south for the winter.
After mating, the female whip-poor-will nests on the ground and lays two eggs on leaves. The female incubates the eggs. The male sometimes incubates, too. The eggs hatch in nineteen to twenty days. The female cares for the chicks, and the male brings them food at night. When the chicks are twenty days old, they can fly.
The female and male may breed again and produce a second clutch of two eggs. If the female is caring for the first brood, the male looks after the second clutch.
Whip-poor-wills and people: The whip-poor-will hides so well that people know the bird mainly by its call.
Conservation status: Whip-poor-wills are not in danger of extinction. ∎
Physical characteristics: Gray nightjars are gray with other plumage coloring that includes brown, black, reddish brown, brownish yellow, and white. Birds range in length from 8.3 to 11.4 inches (21 to 29 centimeters). They weigh from 2.4 to 3.8 ounces (69 to 107 grams). The birds are also called jungle nightjars.
Geographic range: Gray nightjars breed in Asian countries including India, China, and Japan. Birds in the north migrate to Java in the winter. Gray nightjars were seen in Alaska in 2001.
Habitat: Gray nightjars live in rainforests, areas thick with trees and other growth. Birds also live in trees on farms and in other areas.
Diet: Gray nightjars eat insects.
Behavior and reproduction: The female gray nightjar lays two eggs on the ground. She incubates the clutch and may be helped by the male. The eggs hatch in sixteen to seventeen days. The young have reddish brown down (soft feathers). They grow feathers in approximately eighteen days.
Gray nightjars and people: Gray nightjars are rarely seen, but people hear them. The territorial song is said to sound like knocking.
Conservation status: Gray nightjars are not threatened, but are considered rare in India. ∎
FOR MORE INFORMATION
Baicich, Paul J., and Colin J. O. Harrison. A Guide to the Nests, Eggs and Nestlings of North American Birds. San Diego, CA: Academic Press, 1997.
Sibley, David, Allen. The Sibley Guide to Birds. New York: Alfred A. Knopf, 2000.
Stuart, Chris and Tilde. Birds of Africa From Seabirds to Seed Eaters. Cambridge, MA: The MIT Press, 1999.
Burt, William. "Nightjars Are Everywhere But Just Try Finding One." Smithsonian (July 2000): 74.
Global Registry of Migratory Species. http://184.108.40.206/groms/Species_HTMLs/Cindicus.html (accessed on May 29, 2004).
Williams, Ted. "Night Bard of Spring." National Audubon Society earth-almanac. http://magazine.audubon.org/earthalmanac/almanac0405.html#night (accessed on May 25, 2004).