The Indian vulture or long-billed vulture (Gyps indicus) is a bird of prey native to the Indian subcontinent. It is an Old World vulture belonging to the family of Accipitridae. It is a medium-sized vulture with a small, semi-bald head with little feathers, long beak, and wide dark colored wings. It breeds mainly on small cliffs and hilly crags in central India and south India. The Indian vulture is a keystone species that has been listed as Critically Endangered on the IUCN Red List since 2002, as the population has severely declined during the Indian vulture crisis. It is estimated that there are 5,000-15,000 mature individuals in the wild. The main cause of the decline was identified as kidney failure caused by the drug diclofenac, which was commonly given to cattle to reduce joint pain. It is thought that diclofenac poisoned vultures that ate the flesh of dead cattle. Diclofenac bans were enacted in India, Pakistan and Nepal in 2006. The bird shares its habitat with other vulture species in the same genus (particularly the slender-billed vulture (Gyps tenuirostris) and white-rumped vulture (Gyps bengalensis)) in some parts of its range.
Taxonomy The Indian vulture is placed in the genus Gyps (old world vultures), and gets both its common and specific scientific names from its nativity to the Indian subcontinent. The genus name is from Ancient Greek gups meaning "vulture" and the species name is Neo-Latin indicus from the Ancient Greek "indikós" meaning "Indian". The slender-billed vulture (Gyps tenuirostris) was a sub-species of Indian vulture until 2001. Based on nuclear and mitochondrial DNA evidence, it was separated into a different species from the Indian vulture in 2001.
Distribution and habitat The range of the Indian vulture extended from southeastern Pakistan to south India and to Indochina and the northern Malay Peninsula in the east. It is now extinct in South East Asia with current populations existing mostly in central and peninsular India, south of the Gangetic plains. It is also found in southwest Pakistan, Bangladesh and Nepal. It is also found in various land-forms ranging from semi-desert to dry foot hills, open fields and cultivable lands near villages, near garbage dumps and slaughter houses in urban areas. They are not migratory but travel hundreds of miles in a day scavenging for food. Indian vultures nest on cliffs or high buildings and rarely on trees.
Description
The Indian vulture is bulky and medium in size. Its body and covert feathers are pale brown with darker flight feathers. It has white thighs with scattered white fluff and broad wings with short tail feathers. It has a small, bare, dark-brown head with a long featherless neck, dark eyes and a long yellowish beak with a pale green-yellow cere. It is 89–103 cm (35–41 in) long and has a wing span of 2.22–2.58 m (7 ft 3 in – 8 ft 6 in). The bald heads allow them to maintain body temperature in response to the environment. When it is cold, they tuck their necks in closer to their bodies to keep them warm and when it is hot, they extend their necks. Indian vultures have very few feathers on their heads which help them to keep their heads clean when they stick them into the rotting carcasses to feed. It weighs 5.5–6.3 kg (12–14 lb) and is comparatively smaller than the Eurasian griffon. It is distinguished from that species by its less bulky body and wing coverts.
Behaviour and ecology The Indian vulture is a powerful flier and soars on thermal convection currents. It reaches speeds of 35 km/h (22 mph) when gliding and can fly for six to seven hours continuously. The Indian vulture nests mainly on cliffs and is usually found is small flocks, sometimes with other vulture species.
Diet and feeding
The Indian vulture is a keystone species in its habitats and is a scavenging bird, feeding mostly from carcasses of dead animals. It plays a crucial role in the ecosystem by removing rotting meat that would otherwise spread disease. It covers wide areas sometimes ranging hundreds of miles in search of carcasses and mainly uses its eyesight to spot the same. They are often attracted to large gatherings of other raptors or scavengers as this usually means that there is a carrion nearby. The Indian vultures generally feed on dead cattle and any leftovers by large predators. Individual birds often fight with each other to maintain the best position at the carcass. As Indian long-billed vultures are comparatively smaller than some other species, they have to sometimes back down to let other larger birds.
Lifespan and mortality Indian vultures have a lifespan of 40 to 45 years. They sexually mature at five years of age. While vultures in the wild might have a longer lifespan, they are increasingly found close to human habitats. In the human habitats, Indian vultures are prone to higher mortality due to road kills, electrocution on high power lines, collision with trains and other high structures such as windmills. Apart from this, major cause of death has been NSAIDs including Diclofenac commonly given to cattle to reduce joint pain which believed to have been passed onto the vultures thorough the flesh of dead cattle causing kidney failure and death in vultures.
Reproduction
Indian vultures nest on cliffs, high buildings, and, more rarely, on trees. They sometimes build nests on old monuments and towers. A platform of sticks or twigs lined with leaves with the addition of green leaves advertising nest occupancy and fend off parasites. Indian vultures reach breeding age at about five years old. Nest building starts in September and breeding happens between November and March. They often breed in monogamous pairs and the females lay only one egg a year. The egg is pure white or mottled with rusty spots. Both the parents take turns in incubating the egg and the egg hatches in about 50 days. The nests are often located near water sources such as rivers, lakes or ponds to enable them to maintain the humidity levels in the nests. The nests are located at higher altitudes with nearly 90% of the nests at an altitude of more than 900m.
Status and conservation
Population decline and recovery
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