The carrion-eating birds of prey provide a vital service for the environment – cleaning
Vultures prevent the spread of deadly diseases by purging the environment of harmful pathogens
that accumulate on rotting carcasses CREDIT: Kang-Chun Ch (Larger image)
With their bald heads and oily black feathers, vultures have long been reviled as symbols of death and gluttony.
But the carrion-eating birds of prey provide a vital service for the environment – cleaning – and just how important they can be has been calculated by a team of economists.
The sudden collapse of India’s vulture population has led to more than half a million excess human deaths in the last five years, according to a peer-reviewed study in the American Economic Review.
A flock of vultures can pick a carcass clean in a matter of minutes, purging the environment of harmful bacteria and pathogens that accumulate on the rotting remains of livestock and preventing the spread of deadly diseases.
Even the excrement of some species of vulture can carry cleaning powers, with its high acidity helping to disinfect the ground surrounding the dead animal corpses.
But in the 1990s, vulture populations on the Indian subcontinent plummeted by a staggering 99 per cent – the fastest decline of a bird species in recorded history, according to the latest State of India’s Birds report.
For years, scientists were baffled by the sudden extinction. It was only in 2004 that diclofenac – a cheap painkiller widely used to treat cattle that is deadly to vultures if they ingest it – was identified as the cause.
The drug was then banned across South Asia in 2006, after it was discovered that even tiny traces of it could cause devastation to bird populations.
“It all just happened so fast,” said Dr Anant Sudarshan, one of the study’s co-authors and an economics professor at the University of Warwick.
Growing up in New Delhi, Dr Sudarshan remembered seeing large flocks of vultures lining river banks on his journey to school.
“When these birds disappeared, suddenly there were all these dead carcasses lying around…and were no longer delivering these scavenging services,” Dr Sudarshan told The Telegraph. “That change was quite visible.”
The report estimates that the decline caused a four per cent rise in human deaths in districts where the birds once thrived, resulting in more than $69 billion (£53 billion) per year in mortality damages – the economic costs associated with premature deaths.
After the vultures disappeared, the rotting carcasses of livestock animals oozed diseases and bacteria that polluted waterways and fuelled a rise in feral, and sometimes rabid, dogs.
“There are many deep connections between human beings and non-human species in terms of services and ways in which we depend on them,” said Dr Sudarshan.
“India generates a lot of cattle and when those cattle die, those carcasses need to be scavenged. This is particularly true in India, because the cow is a holy animal. You don’t have a lot of beef being eaten.”
Scientists have warned that governments in Europe and South Asia are still failing to sufficiently regulate veterinary drugs to protect vultures.
Seven out of 11 of the vulture species found in Africa, responsible for cleaning up 70 per cent of the continent’s carrion, are now on the verge of extinction. Diclofenac is also still in circulation.
“Africa is much less densely populated than India. So the change is not as sudden, but it will get there,” said Dr Sudarshan.
Dr Eyal Frank, an assistant professor at University of Chicago and one of the authors of the study, said that the report serves as a warning of “how bad it can get when a component of the ecosystem collapses.”
The birds are synonymous with death and gluttony – but their plummeting numbers could spell serious trouble for humans.
Click image for larger view
A catastrophic decline of vulture populations in Africa and Asia is causing alarm among researchers, who fear that a “cascade” effect could lead to the spread of deadly old and new diseases, including plague, anthrax, and rabies.
The report highlights the large value of ecosystem services from so-called keystone species – those that help tie the ecosystem together – and recommends for policy makers to focus on them when targeting conservation and protection efforts.
“We think of these kinds of statements about human beings being kind of intertwined with nature as this kind of hippie concept, but it’s [actually] quite mechanical and instrumental,” said Dr Sudarshan, adding that he was optimistic that the message was beginning to getting through.
“I think this is happening in the background…ecologists have pointed out that the planet is in the midst of its sixth mass extinction in history.”
Previous mass extinction events have been caused by climate change, meteors and even dinosaurs dying out. But the current one is caused by “human activity,” the report said.
“We are introducing a lot of toxins into the environment and introducing a lot of changes to habitats…but we aren’t broadening our risk assessment of things that directly harm us,” said Dr Sudarshan.
“If we don’t broaden it beyond what directly harms human beings …then we’re going to risk seeing more and more of these [extinctions]…and it’s not easy to reverse,” he warned.
By Lilia Sebouai – Source
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