Caprimulgus macrurus

Written by on April 13, 2012 in Indonesia Bird with 0 Comments

Caprimulgus macrurus, Large-tailed Nightjar,  Cabak Maling


Large-tailedNightjars feed on moths and other night-flying insects. They are particularly fond of flying termite swarms.

They perch-and-wait then swoop down and catch prey on the wing, flying low over the ground, swerving from side to side. Long pointed wings and tails make them acrobatic and silent fliers. They sometimes perch on street lamps, snapping up the insects attracted to the light, particularly after heavy rains. Or they may fly slowly about while keeping a look out (quartering). They are most active at dusk.

Their bills can enlarge into an enormous scoop to catch insects in flight. Short but wide, the bill has a special joint half way along the length on either side which allows the tip of the beak to drop even lower. They have a line of bristle-like feathers fringing the beak.

Suggestions for the function of these bristles include: to funnel insects into the mouth; deflect insects from the eyes; or act like whiskers to detect prey so the bird knows when to snap its bill shut.
Nightjars have a serrated comb-like portion on the inner middle toe (like some bitterns, owls and pelicans). These may be used to comb out insect debris from their facial feathers.
During the day, Nightjars sit motionless on the ground, perfectly camouflaged among the leaf litter. Often they will remain unmoving until you almost step on them. They may also perch on a low branch.

The Nightjar has a brightly coloured mouth, which it may suddenly gape open to startle a predator, thus giving the Nightjar a head start in making its escape.

Breeding (Mar-Jun): When two Nightjars are near each other, they make a low frog-like croaking which could be part of a pair bonding ritual. They call often during breeding season, from a pole or branch.

Nightjars don’t make a nest and simply lay 1-2 mottled buffy/pinkish eggs on the ground in a shallow depression. They nest in the open, usually in a shaded area, under a tree or bush. The eggs are perfectly camouflaged and look like pebbles. Eggs average 8-9gm, the first egg is usually heavier and larger. Both parents take turns brooding the eggs which hatch in 16-18 days.

The chicks emerge with down feathers and can move away from the nest site 1-2 days after they hatch. To avoid detection, the chicks keep changing their rest spot every night, sometimes siblings rest up separately. During the day, among dead leaves in the undergrowth, the babies’ mealy brown feathers camouflage them perfectly. It appears only the female cares for the young until they can fly. Like other ground-nesting birds, she will distract predators by moving away from her eggs or chicks while pretending to have a broken wing. The young are not helpless and when threatened, flap their wings with their bills wide open, lunging forwards in self defence.

In Europe, Nightjars follow night-foraging domestic livestock, eating the insects disturbed by the bigger creatures. People thought the birds fed on the milk of these domesticated animals and mistakenly called the birds “goat-suckers”.

Migration? Nightjars don’t appear to migrate. They are found in forest edges and open but humid areas such as mangroves, forest edge, scrub, cultivated lands. They are not common in the deep forest.

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