Why You Should Love Vultures Part 1: Misunderstood until it was almost too late
“For years condemned as harbingers of death, the value of vultures has only been realised when they (themselves) are virtually at death’s door.”
Prerna Singh Bindra, author of The Vanishing – India’s Wildlife Crisis
If you were born before 1994 you have essentially lived through one of the most dramatic, and significant, near extinction events in recent history, and the fastest decline of any bird species ever reported anywhere in the world. Forget for a moment the pterodactyl, the dodo and the oft-cited passenger pigeon, and spare a thought instead for the much misunderstood vulture.
Nature’s clean up merchants might not be deemed the most aesthetically pleasing or elegant of beasts to the human eye, but they are highly intelligent, very social and play an absolutely vital role in servicing ecosystems and controlling disease. Their unprecedented decline in the Indian sub-continent has been not just tragic but dangerous to animals and people alike. And what’s particularly sad is that, perhaps because the value of vultures wasn’t fully appreciated, no-one really noticed until it was almost too late.
At the beginning of the 1990s, vultures were so common in India that biologists wouldn’t even count if they saw less than five in number together. They were everywhere. One limited survey has since been extrapolated to suggest that there were about 40million birds, and the RSPB estimates that the oriental white-backed vulture was probably the most common bird of prey in the world at the time.
Just a decade later, the number of white-rumped vultures (Gyps bengalensis) alone had crashed by a staggering 99.9%, leaving just one in a thousand alive, and making it the then most imperilled bird of prey in the world. The numbers of two other species, the long-billed vulture (Gyps indicus) and the slender-billed vulture (Gyps tenuirostris), also dropped by 97%. And no-one knew why. By 2000, all three species had been declared Critically Endangered by the IUCN.
To try and understand the scale of this unprecedented decline, you can think of it as representing 5,000 birds dying every day for 15 years.
But what was causing it?
What had happened?
Getting to the bottom of the mystery of what was behind the decimation of vulture numbers, not just in India but also in Pakistan and Nepal, was not easy. Eventually, in 2004 an international team of scientists testing vulture carcasses in Pakistan, under the guidance of the Peregrine Fund, successfully identified the culprit as the non-steroidal anti-inflammatory drug diclofenac, which had become a cheap and popular way of treating pain and fever in cattle. While the drug, which cost less than 50 US cents a dose, was a godsend for local cattle owners, tests revealed that it quickly caused renal failure and death in vultures which fed on the carcasses of cattle that had recently been treated with it. With India being the country with the world’s largest cattle population, the bodies of cattle left in carcass dumps were the most common food source for scavenging vultures. On further investigation, the drug had only been adopted for veterinary use in the early 1990s, after the original patent expired, making it possible to produce cheaper generic versions for the local market. As a result, it quickly came to be used by vets and farmers on a massive scale, and 11% of dead cattle in carcass dumps had diclofenac in their tissues. The vital link had been made.
Why did it matter?
No one does it like a vulture can. Vultures are unparalleled in their ability to quickly and efficiently strip a carcass. Working together, they can strip a cow or deer down to the bone in as little as twenty minutes, so that there is no meat left to rot, and no chance for nasty pathogens which may have been present in the carrion to thrive. Vulture stomach acid is so powerful that they are effectively a dead-end for many harmful pathogens, which means they don’t in turn become carriers of disease.
Before the catastrophic crash in their numbers, vultures were estimated to safely dispose of 12 million tons of carrion annually in India. With their demise, millions of carcasses were left to rot, increasing the risk of diseases like anthrax, TB and brucellosis, and leading to an explosion in numbers of other less efficient scavengers. It’s estimated that in the absence of vultures, carcasses take up to three to four times longer to decompose. Unfortunately, species likes rats and feral dogs which expanded to fill the vacuum typically themselves become carriers and spreaders of pathogens, including zoonotic diseases like brucellosis and rabies, a risk accentuated by the fact that they are also species that tend to coexist closely with humans.
What happened next?
Once diclofenac had been confirmed as the source of the problem, rapid action by range state governments to ban the veterinary use of the drug, and encourage the use of meloxicam as an alternative, as well as huge coordinated conservation efforts, meant that the Indian subcontinent’s vultures were pulled back from the brink of extinction. Nevertheless, they are still extremely vulnerable, partly due to ongoing illegal use of diclofenac and use of other NSAIDs which we now know are also toxic to vultures, but also to the fact that vultures do not breed rapidly. They don’t reach maturity until they are five, spend six weeks building a nest, only lay one egg a year and have an eight month breeding cycle. It was previously estimated that there was little hope for survival if the loss of the species was running at more than 5% a year. As numbers plummeted, the rate of loss for the white-rumped vulture was running at nearly45% a year. It is therefore clear testimony to the intense and well-coordinated efforts to save them that by 2017 numbers of the most threatened species were estimated at 1,000 slender-billed, 6,000 white-rumped and 12,000 long-billed. But vultures are still far from out of the woods.
There is much still to be done. Watch out for our next articles, which will look in more detail at why vultures are so important to ecosystem and human health, the remarkable cooperative efforts that have been made to save them so far, and how WVI will be supporting ongoing efforts to ensure these unique and incredible birds survive and thrive.
In the meantime, please become a vulture champion and tell everyone you can about why we should all love these much misunderstood birds.
Figure from RSPB/Bombay Natural History Society