White-rumped Vulture - Behaviour and Ecology

Behaviour and Ecology

These birds are usually inactive until the morning sun has warmed up the air with sufficient thermals to support their soaring. They circle and rise in altitude and join move off in a glide to change thermals. Large numbers were once visible in the late morning skies above Indian cities.

When a kill is found they quickly descend and feed voraciously, and will perch on trees nearby and are known to sometimes descend even after dark to feed on a carcass. When feeding at carcasses they are dominated over by Red-headed Vultures Sarcogyps calvus. A whole bullock has been said to have been cleaned up by a pack of vultures in about 20 minutes. In forests, the sight of their soaring was often the indication of a tiger kill. They may also swallow pieces of bone. Where water is available these birds bathe regularly and also drink water.

Allan Octavian Hume noted based on the observation of "hundreds of nests" that they always nested on large trees near habitations even when there were convenient cliffs in the vicinity. The preferred nesting trees were Banyan, Peepul, Arjun, and Neem. The main nesting period was November to March with eggs being laid mainly in January. The male initially brings twigs which are arranged to form the nest by the female. Courtship involves the male billing the head, back and neck of the female. The female invites copulation and the male mounts and hold the head of the female in his bill. Several pairs may nest in the vicinity of each other and isolated nests tend to be those of younger birds. Solitary nests are never used regularly and are sometimes taken over by the Red-headed Vulture and large owls such as Bubo coromandus. Nests are nearly 3 feet in diameter and half a foot in thickness. Prior to laying an egg, the nest is lined with green leaves. A single egg is laid which is white with a tinge of bluish-green. Female birds are reported to destroy the nest on loss of an egg. They are usually silent but make hissing and roaring sounds at the nest or when jostling for food. The eggs hatch after about 30 to 35 days of incubation. The young chick is covered in grey down. The parents feed them with bits of meat from a carcase. The young birds remain for about three months at the nest.

Trees on which they regularly roost are often painted white with their excreta and this acidity often kills the trees. This made them less welcome in orchards and plantations.

A freak case of a bird getting caught in the mouth of dying calf and dying trapped within has been noted. Mycoplasmas have been isolated from tissues of the bird. Mallophagan parasites such as Falcolipeurus and Colpocephalum turbinatum have been collected from the species. Ticks, Argas (Persicargas) abdussalami, have been collected in numbers from the roost trees of these vultures in Pakistan. A specimen in captivity lived for at least 12 years.

Jungle Crows have been seen to steal food brought by adults and regurgitated to young. They may sometimes feed on dead vultures of their own species while Egyptian Vultures have also been noted to feed on dead vulture fledgelings.