July 2014: Recent vulture mortalities in Assam and the need to keep the removal of diclofenac in India a priority

Just this year, there has been a series of vulture mortality events reported in Assam. One hundred and seventy-nine vultures have been killed in seven separate incidents. The majority of the dead vultures are Himalayan (Griffon) Vultures, but significant numbers of Oriental white-backed vultures have also been killed, as well as several slender-billed vultures. Samples of many of these vultures have been sent for analysis either at local labs or BNHS to determine cause of death.

Almost all vultures were found dead close to a carcass of a domesticated animal; therefore, the likely cause of death is incidental poisoning through the consumption of tissue from a carcass deliberately laced with poison to kill dogs and/or wild carnivores. Such poisoning events are not new; and have probably been occurring for a long time in Assam and other parts of India, but it may be increasing as a consequence of the vulture declines. Numbers of feral dogs (and maybe other mammalian scavengers) have increased in response to the disappearance of vultures and the subsequent abundance of available carcasses. This creates new problems for livestock keepers and others for whom dogs are a nuisance and may lead to an increase in poisoning events.

Diclofenac-related vulture deaths in India are still almost certainly far greater than those related to incidental poisoning, but the evidence is not always apparent. The chemicals used to poison carnivores typically kill vultures immediately and thereby their corpses are found near the poisoned carcass. By contrast, diclofenac typical kills vultures after two days, allowing vultures to disperse before dying and thereby their corpses are separate and rarely noticeable or newsworthy.

Nevertheless, incidental poisoning is apparently becoming more frequent. This is a worrying trend, especially when vulture populations are small. We certainly need to highlight this as a serious threat in addition to diclofenac and do more to avoid it happening in future.

If we can get SAVE’s immediate priorities of 1) a ban on multi-dose vials of human diclofenac and 2) all non-steroidal anti-inflammatory drugs safety tested on vultures (see 4th SAVE report for more details) then we can focus our attention more specifically on addressing incidental poisoning.

Note that it is partly the result of community awareness-raising activities by BNHS and other groups, such as the Wildlife Trust of India, that we are hearing more about incidental poisoning. In response, raising awareness on incidental poisoning is now incorporated into BNHS’s work.