Indian vulture

An Indian vulture flying

The Indian vulture is a keystone species in their habitats and are scavenging birds, feeding mostly from carcasses of dead animals.[17] It plays a crucial role in the ecosystem by removing rotting meat that would otherwise spread disease.[18] It covers wide areas sometimes ranging hundreds of miles in search of carcasses and mainly uses its eye sight to spot the same.[14]

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.[9]

Indian vultures have a lifespan of 40 to 45 years. They sexually mature at five years of age.[19] 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.[20][21][22] 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.[17]

Indian Vultures nesting on a cliff

Indian vultures nest on cliffs or high buildings and rarely on trees. They sometimes build nests on old monuments and towers.[11][23][9] 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 for incubation. The nests are located at higher altitudes with nearly 90% of the nests at an altitude of more than 900m.[12] a platform of sticks or twigs lined with leaves with the addition of green leaves advertising nest occupancy and fend off parasites.[23] Indian vultures use the same nest for multiple years as nest building is a highly energy consuming activity.[12]

Indian vultures reach breeding age at about five years old. Nest building starts in September and breeding happens between November and March.[23] They often breed in monogamous pairs and the females lay only one egg a year.[24] 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.[11]

Indian vultures are slow and difficult breeders

Beginning in the 1990s, the Indian vulture species has suffered a 97% population decrease in its range in the Indian subcontinent over a period of 10-15 years.[25] The species is classified as critically endangered in the IUCN Red List since 2002 due to the rapid decline in population.[1] Currently, there are only an estimated 5000 to 15000 birds in the wild.[26]

This is conjunction with the rapid decline in the population of other related vulture species including the slender-billed vulture and white-rumped vulture. Between 2000 and 2007, the annual decline rates of this species averaged over sixteen percent.[26] The cause of this rapid decline was identified as poisoning caused by the veterinary drug diclofenac. Diclofenac is a non-steroidal anti-inflammatory drug commonly given to cattle to reduce joint pain. The drug is believed to have been passed onto the vultures thorough the flesh of dead cattle who were given diclofenac in their last days of life which then causes kidney failure in vultures.[17]

Data modelling revealed that a tiny proportion (about 0.8%) of livestock carcasses containing diclofenac can cause significant crash in vulture populations.[24] The decline in vulture population had a huge socio-economic impact in the region and drastically affected the conservation of the ecological balance. By removing all carrion, vultures had helped decrease pollution, spread of diseases, and suppressed undesirable mammalian scavengers.[27] Without vultures, a large number of animal carcasses were left to rot posing a serious risk to human health by contaminating water supply and providing a potential breeding ground for infectious germs and proliferation of pests such as rats.[28] The loss of vultures also resulted in a substantial increase in the population of feral dogs, whose bites are the most common cause of human rabies. The feral dog population in India increased by least 5 million, resulting in over 38 million additional dog bites and more than 47,000 extra deaths from rabies, costing $34 billion in economic impact.[17] On average, it was estimated that human mortality rates increased by more than 4% during the period of 2000 to 2005, when vulture population reached the lowest levels.[29]

In March 2006, the Government of India announced a ban on the veterinary use of diclofenac. Meloxicam, another NSAID was rapidly metabolized and harmless to vultures was suggested as an acceptable substitute for diclofenac.[30] Pharmaceutical companies were encouraged to the increase in the production of meloxicam aimed at reducing the cost down to diclofenac's own levels to make it more suitable for use. In 2015, Government of India ordered the vial size of the drugs to be reduced to 3ml to reduce the dosage administered to cattle.[24] In 2021, tolfenamic acid was identified as another alternative that is safe for vultures.[31][17]

Post banning the drug in 2006, the vulture population rebounded and with the combined population relatively stable till 2011. But, further decline of vulture populations were reported in some states in India.[7] Despite the banning of diclofenac and reduction in usage by about 50%, the drug was still available for veterinary use.[32] There were other compounds like aceclofenac and ketoprofen which were in use and were harmful.[33] In 2008, Government of India enacted a law declaring the sale of diclofenac as a imprisonable offense.[17] Later surveys found that the population was recovering slowly and the decline has been significantly arrested in India, Pakistan and Nepal following a strict ban on the drug.[7][17][34]

Captive-breeding programmes for the Indian vulture were started to help recover its numbers. As the vultures are long lived, slow breeding and notoriously difficult to breed in captivity, the programmes are expected to take longer. The captive-bred birds will be released to the wild when the environment is clear of diclofenac.

In 2014, Saving Asia's Vultures from Extinction programme was announced to start releasing captive-bred birds into the wild by 2016.[35] In 2016, Jatayu Conservation Breeding Centre in Pinjore released captive bred vultures into the wild as part of Asia's first vulture re-introduction program.[36] Small numbers of birds have bred across peninsular India, in Karnataka and Tamil Nadu.[37] Three more breeding centers have been setup in the Indian states of West Bengal, Assam and Madhya Pradesh in addition to four smaller facilities in collaboration with zoos.[24]

In 2020, the Ministry of Environment, Forest and Climate Change of Government of India has launched a Vulture Action Plan 2020-25. It aims to step up conservation measures and set up a mechanism to ensure that toxic drugs other than diclofenac are also banned for veterinary use.[33]

In 2010, a small population of Indian vulture and three other species of vultures were discovered in the Moyar river valley in Sathyamangalam Wildlife Sanctuary in Tamil Nadu. 20 nests were sighted with a population of 40 adults. It was last sighted in the region in the 1970s and the rediscovery is significant to its conservation.[38][39]