19 Dec 2017

New study: India may have even fewer vultures than we thought

India’s Critically Endangered vulture populations seemed to be stabilising, but a new study has revealed that numbers may be even fewer than we thought. Although vulture-killing livestock drug diclofenac has been banned, there are other drugs, equally fatal to vultures, that have not – and this is thought to be the main cause.

The Indian Vulture is one of three vulture species reassessed in a new paper released today © Sudipto Roy
The Indian Vulture is one of three species reassessed in a new paper released today © Sudipto Roy
By Jessica Law

Talk about no good deed going unpunished. Throughout the 1990s and 2000s, South Asia’s vulture populations underwent catastrophic declines, the vultures dying while performing their most essential and valued ecosystem service to humans: disposing of cattle carcasses. These remains would otherwise be left to feed and boost the populations of problem scavengers like feral dogs, or cost the government untold sums to clean up. The main reason for these devastating deaths was a veterinary drug called diclofenac: a painkiller for cattle, but a poison to vultures.

Today, three of India's resident vulture species - the Slender-billed Vulture Gyps tenuirostris, White-rumped vulture Gyps bengalensis and Indian Vulture Gyps indicus - are considered Critically Endangered, despite formerly numbering tens of millions.

But how many of these beleaguered birds of prey actually remain?

That’s what conservationists have been trying to find out. The Bombay Natural History Society (BNHS – BirdLife in India) and the RSPB (BirdLife in the UK), working as part of Saving Asia’s Vultures from Extinction (SAVE), have been monitoring these species since before the crash. Every four years, they set out on a survey of epic proportions, covering 15,500km of road in 13 states across India, counting individual vultures of each of the three species.

 

White-rumped Vulture populations appear to be on the increase © Natasha Peters

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For a while, things looked pretty grim. Then, in 2012, they reported a slowing-down in the declines of all three species, with possible signs of recovery in the White-rumped Vulture. These encouraging findings made the headlines.

Now, new methods have resulted in more accurate findings. In a paper published and freely available in Bird Conservation International today, the BNHS-RSPB team give updated estimates of the population size, and the upward – or downward – trends for all three species. The estimates for population size now take into account whether the data was collected close to protected areas, where vultures are relatively more common. As a result, they provide a more accurate picture than the team’s earlier estimates.

But the results are not all positive. The good news is that White-rumped Vulture populations still seem to be on the increase. The bad news is that the Indian Vulture population continues to decline. Worse, the number of Slender-billed Vultures they counted are now too small to estimate a reliable trend. This new information has been used to back up BirdLife’s global estimates, and support the Vulture Multi-species Action Plan

Vulture numbers are “alarmingly low”

According to Dr Vibhu Prakash, lead author of the paper and Principal Scientist for the BNHS: “The new best estimate of population size for all three species is much lower than previously thought. In 2015, we estimate there were approximately 6,000 white-rumped vultures, 12,000 long-billed vultures and 1,000 slender-billed vultures. These numbers are alarmingly low.”

 

There could be only a thousand Slender-billed Vultures (centre) remaining in India today © J Irons

 

So why are populations still so depleted? Well, diclofenac remains a problem, despite a long battle to eradicate it. The painkiller was banned for veterinary use way back in 2006 throughout India and neighbouring countries, but pharmaceutical companies continued to produce diclofenac in suspiciously large vials – allegedly as “multi-packs” for human use, but easily re-purposed for livestock. Then in 2015, The Government of India banned these large vials of diclofenac too. This year, in a final, desperate attempt to grasp profits, two Indian pharmaceutical companies legally challenged this second ban, but fortunately it was upheld by the Madras High Court. The hope is that this will signal a final end to the problem painkiller.

“The vulture crisis in India is not over”

But it’s not just diclofenac. Diclofenac is only one of over a dozen drugs known as non-steroidal anti-inflammatory drugs (NSAIDs) available in India. We know that one, called meloxicam, is non-toxic to vultures. But we also know that four others (aceclofenac, carprofen, flunixin, ketoprofen and nimesulide) are toxic. And their threat is arguably far greater than diclofenac, because they are all still legal.

It’s not all bad news, but it’s clear that a lot more work is needed. Dr Toby Galligan, co-author of the paper and Senior Conservation Scientist for the RSPB Centre for Conservation Science, sums up the situation: “Our paper is reminder that the vulture crisis in India is not over, and more regulatory actions on vulture-toxic NSAIDs need to happen to save India’s vultures from extinction.” 

Read the full paper here, and find out more about the vulture crisis here.