Once abundant and widely seen across India, vultures once soared over vast landfills and scavenged cattle carcasses. Their presence was so common that they occasionally posed hazards to aircraft by being sucked into jet engines during take-offs.
However, over the past two decades, India’s vulture population has suffered a drastic decline due to a drug used in treating sick cattle. In the mid-1990s, the vulture population of 50 million plummeted to near extinction because of diclofenac, a cheap non-steroidal anti-inflammatory drug. When vultures consumed the carcasses of cattle treated with diclofenac, they suffered kidney failure and died.
Despite a 2006 ban on the veterinary use of diclofenac, the population decline has continued, with at least three vulture species experiencing long-term losses of 91-98%, according to the latest “State of India’s Birds” report.
Furthermore, a new peer-reviewed study, published in the American Economic Association journal, reveals that the collapse of vulture populations led to a rise in deadly bacteria and infections. This ecological imbalance is estimated to have resulted in the deaths of approximately half a million people annually over five years.
“Vultures are considered nature’s sanitation service because of the important role they play in removing dead animals that contain bacteria and pathogens from our environment – without them, disease can spread,” says Eyal Frank, an assistant professor at the University of Chicago’s Harris School of Public Policy and co-author of the study.
“Understanding the role vultures play in human health underscores the importance of protecting wildlife, and not just the cute and cuddly. They all have a job to do in our ecosystems that impacts our lives.”
Mr. Frank and his co-author, Anant Sudarshan, analyzed human death rates in Indian districts that previously had high vulture populations compared to those with historically low numbers of vultures, both before and after the vultures’ decline. They also investigated sales of rabies vaccines, counts of feral dogs, and pathogen levels in water supplies.
Their research revealed that in districts where vultures had once been abundant, human death rates increased by over 4% following the collapse of vulture populations and a rise in sales of anti-inflammatory drugs. The impact was most pronounced in urban areas with significant livestock populations and frequent carcass disposal sites.
The study’s authors estimated that between 2000 and 2005, the decline in vulture populations resulted in approximately 100,000 additional human deaths each year. This surge in mortality came with a staggering economic toll of over $69 billion (£53 billion) annually, reflecting the costs associated with these premature deaths.
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The absence of vultures, which had once played a crucial role in cleaning up carcasses, led to a significant increase in disease and bacteria in the environment. With vultures gone, the stray dog population surged, bringing a rise in rabies cases among humans. Although rabies vaccine sales increased during this period, they proved inadequate in addressing the problem.
Unlike vultures, stray dogs were inefficient at removing decaying remains, which allowed bacteria and pathogens to proliferate. Consequently, runoff and improper disposal of these remains led to a dramatic rise in fecal bacteria levels in drinking water, more than doubling the contamination.
“The vulture collapse in India provides a particularly stark example of the type of hard-to-reverse and unpredictable costs to humans that can come from the loss of a species,” notes Mr. Sudarshan, an associate professor at the University of Warwick and co-author of the study.
“In this case, new chemicals were to blame, but other human activities – habitat loss, wildlife trade, and now climate change – have an impact on animals and, in turn, on us. It’s important to understand these costs and target resources and regulations towards preserving especially these keystone species.”
Among the vulture species in India, the white-rumped vulture, Indian vulture, and red-headed vulture have faced the steepest declines since the early 2000s, with populations plummeting by 98%, 95%, and 91%, respectively. The Egyptian vulture and the migratory griffon vulture have also seen significant drops, though not as severe.
According to the 2019 livestock census, India recorded over 500 million animals, the highest count globally. Vultures, known for their exceptional scavenging abilities, were once vital to farmers for rapidly disposing of livestock carcasses. The speed of the vulture population decline in India is unparalleled, marking the most drastic decrease observed for a bird species since the extinction of the passenger pigeon in the US.
Today, the surviving vulture populations in India are mainly found in protected areas where they feed more on dead wildlife rather than contaminated livestock. However, ongoing declines in vulture numbers continue to pose serious threats, with repercussions for both wildlife ecosystems and human health, as highlighted by the State of Indian Birds report.
Experts continue to sound the alarm over the persistent threats facing India’s vulture populations. Veterinary drugs remain a significant hazard, with dwindling carcasses—due to increased burial practices and competition from feral dogs—intensifying the crisis. Additionally, quarrying and mining activities threaten to disrupt critical nesting habitats for some vulture species.
The future of vultures in India remains uncertain, though there are glimmers of hope. Last year, a noteworthy initiative saw 20 vultures, bred in captivity and equipped with satellite tags, released from a tiger reserve in West Bengal. Furthermore, recent surveys in southern India recorded more than 300 vultures, indicating a modest recovery. However, experts stress that continued and expanded efforts are essential to ensure a more robust comeback for these crucial scavengers.
(Includes inputs from online sources)
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