A massive die-off
So what would the world look like, if vultures suddenly disappeared? Unfortunately, we don’t have to guess. In India, one of the most devastating wildlife disasters of the past century can answer that question.
In the early 1990s, a painkiller called diclofenac became available in a new and affordable generic form in India.
Farmers quickly realized that this generic diclofenac, which has been a safe and widely used human drug for decades, was highly effective at treating inflammation and other pain in their livestock. They adopted it quickly and almost universally across India, a country with over 500 million livestock animals.
“What they didn’t know is that even small residue amounts of the active ingredient in a carcass that a vulture eats will cause kidney failure, and lead to their death within a few weeks,” says Eyal Frank, a University of Chicago economist who co-wrote an upcoming paper in the journal American Economic Review that compares human death rates at the local level in India.
The crisis that followed was historic in its speed and scope. The three most common species of vultures in India, all closely related members of the genus Gyps, once numbered in the tens of millions, but over 90 percent of Gyps vultures in India died in less than a decade.
The Indian vulture collapse is one of the fastest declines of any bird in history, rivaled only by the intentional mass killing of sparrows during Mao Zedong’s “Four Pests” campaign in the late 1950s.
Quickly, it became obvious that India was dependent on vultures to clean up the millions of carcasses of cows, sheep and other livestock animals that died each year across the country.
Without the infrastructure to incinerate and otherwise process carcasses, the shock of the sudden vulture collapse led to animal bodies quickly piling up. A public health emergency followed, the depth of which researchers are just now starting to understand.
The cost in human lives
Frank and his co-author, economist Anant Sudarshan of the University of Warwick in England, looked at death rates at the local level in India.
They found that before the collapse, death rates in areas with high vulture populations and areas with fewer vultures tracked fairly closely together. But after diclofenac decimated vulture populations, the formerly vulture-heavy districts saw a rise in annual deaths of about 4 percent.
Hundreds of millions of people lived in those newly vulture-deprived districts, and Frank and Sudarshan’s math led to a striking conclusion: There had been over 100,000 additional human deaths per year, for at least five years, after the vultures disappeared. They attributed these deaths to increased rates of diseases like rabies, as well as decreased water quality — vultures help prevent water contamination from decomposing carcasses.
“The vulture die-off was an unintended effect of development,” says Saudamini Das, a professor of economics at the Institute of Economic Growth in Delhi.
This year, Das co-wrote a paper in the journal Environment, Development and Sustainability looking at the economic costs of the diclofenac crisis, and the costs and benefits of bringing vultures back.
In addition to the loss of life and health, the vulture crash was costing India billions. The cleanup that vultures had done for free now had to be accomplished with human crews and vehicles, and expensive new facilities like rendering plants.