The Parable of the Vulture

“You can never do merely one thing.” — Garrett Hardin, ecologist

As fellow animals, our ancestors of old did not walk unseeing in the forests, plains and mountains. They took time to marvel at the sheer intensity of the lives of their sisters and brothers. The terror and beauty of it all.

Now we just call them species. And we dutifully count their disappearance like accountants who prize only the art of subtraction.

Each extinction, no matter how big or small, creates a ripple. That wave intensifies a death knell in ways rarely appreciated let alone understood.

This brings me to the parable of the vulture which is the unlikely subject of an economics paper that made headlines last week.

At one time more than 50 million vultures surfed the skies in kettles over India, Pakistan and Nepal. The most abundant bird of prey in the world appeared so numerous that people didn’t bother counting them in bird surveys. Now the accountants can do that: there are barely 20,000 left. “Functionally extinct,” they call it.

Vultures used to take care of the decomposing dead. The white-backed vulture (Gyps bengalensis), the long-billed vulture (Gyps indicus) and the slender-billed vulture (Gyps tenuirostris) would descend from the sky and alight upon a dead cow, an expired buffalo or even a departed Parsi resting in a Tower of Silence.

Within 40 minutes the sharp beaks of 100 vultures could reduce putrefying flesh to glistening bone. Like us they rejoiced in communal dining. With their long featherless heads, India’s vultures excelled at pulling meat from the bowels of a hoofed animal.

Eating dead things, of course, requires an iron gut. A vulture’s highly adaptive stomach can handle any pile of rotting flesh along with pathogens as deadly as anthrax. A vulture’s digestive system is 100 times more acidic than a human’s. Vultures, along with beetles and bacteria, make up one of nature’s finest sanitation crews.

For thousands of years the people and farmers of India prized and characterized this relationship as purifying. Religion and necessity shaped this lengthy entanglement. Hindus don’t slaughter or eat beef. On a continent with more than 500 million livestock (mostly cows), villagers simply counted on vultures to take care of the dead.

Whenever a cow faltered, farmers stripped off the leather. Then they disposed of the carcass near nesting colonies on the outskirts of town or in dumps. In this fashion vultures disposed of nearly 27 million dead cows, camels and water buffalo a year. Bone collectors picked up the remains to use as plant fertilizer.

This avian disposal service kept the dead from stinking up the place and fouling waterways. It kept in check the spread of rabies, brucellosis and tuberculosis.

But in 1994 vultures began dying in heaps. The eaters of the dead became themselves carrion. Their long wings no longer soared through thermals. Their silhouettes vanished from treetops and old ruins. The raptor biologist Vibhu Prakash entered a familiar bird sanctuary south of Delhi and discovered a tragedy: an abundance of 1,800 birds had become 86. Villagers asked, “Where are the vultures?”

The birds died in trees and fell from their perches. Heat and stray dogs made it difficult to find a whole bird for chemical tests. When Prakash did find one, and then another, the autopsies invariably found something unusual: visceral gout. The bird’s internal organs contained an eruption of uric acid crystals. The vultures were dying of kidney failure.

By the end of that decade nearly 95 per cent of India’s wild vultures had been silenced. Researchers called it the fastest collapse of a bird population since the extermination of passenger pigeons in North America. Those gregarious birds, which once formed flowing rivers in the sky, went from billions to zero in 100 years. People ecstatically slaughtered them to make a tasty pigeon pie. The last pigeon was named Martha. She died alone in the Cincinnati Zoo in 1914, like an elder in a long-term care facility.

The monumental collapse of the vulture population left millions of dead cattle on the landscape. The rotting meat piles spread disease, and polluted waterways. In their absence rats and feral dogs exploded in number. India has the highest number of stray dogs in the world, and highest number of human deaths from rabies. "Yes, the dogs are many now that the long-necked vultures are gone," an animal skinner told a Smithsonian reporter.

The consequences gathered speed like some ghostly avalanche. That resulted in over 38 million additional dog bites. The bites resulted in more than 47,000 extra deaths from rabies. And on it went.

The disappearance of India’s vultures also created a conundrum for the Parsi, religious migrants from Persia. The Parsi believe that cremation and burial of the dead are unholy acts. Instead, they place their departed on Towers of Silence for vultures, kites and crows to devour. But a job that used to take minutes with vultures now took weeks of uncertain decomposition. The Parsi even added solar reflectors to their towers to accelerate decay, but with little effect.

For 10 years an international team of scientists searched for the cause of the great dying. They tested for viruses, heavy metals and pesticides. In frustration they changed their focus and looked at what the vultures were eating: dead cows. And here they discovered a small change with big consequences.

In 1994 the international patent for diclofenac, the world’s most common anti-inflammatory drug, expired. It had been held by the Swiss firm, Ciba-Geigy, which later became Novartis.

In response as many as 50 Indian companies started to knock off a variety of cheap generic brands for people. They also expanded the drug’s scope to treat aches, mastitis, fever and pain in India’s 300 million cows. Between 1991 and 2003, diclofenac sales in India shot up almost tenfold. Although harmless to cattle, just a tiny dose became a huge poison for vultures.

A Cambridge zoologist did the math. It would take only 0.1 to 0.8 per cent of livestock carcasses to contain enough diclofenac to account for the functional extinction vultures. Prakash and colleagues collected tissue samples from almost 2,000 livestock carcasses. Almost 10 per cent contained diclofenac. In some regions the figure reached 20 per cent. Every meal became a death warrant for the vulture.

The pain and suffering of 50 million dying birds over the space of a decade was rarely comprehended. The Australian Thom Van Dooren, the author of Vulture, gave it a try because the data on the dead “fails absolutely in capturing what that something is that is actually lost.”

On average it took two days for a vulture to die, noted Van Dooren. Anyone who has ever experienced gout can imagine the devilish inflammation, the aching joints, the night fevers of pain with no hourly relief. As the internal organs ballooned and failed, lethargy and depression took over. At that point the proud neck of a vulture begins to droop. And then the dying bird falls to Earth, another casualty of the sixth extinction caused by the technology of humans.

The Indian government didn’t ban the veterinary use of diclofenac until 2006. Meanwhile rampant illicit use flourished because the drug efficiently extended the lives of sick cows. Moreover, the biologist Prakash later identified three other veterinary anti-inflammatories — ketoprofen, nimesulide and aceclofenac — just as toxic. Only two were banned in 2023.

At this point two economists, one in Chicago and another in Warwick, entered the story. They calculated that the cascading effects of feral dogs, animal bites and rabies “may have resulted in an extraordinarily large, negative sanitation shock to human populations.” That’s how economists talk. It is a different language.

They scoured public records and that’s indeed what they found. As the vultures disappeared in many districts, health records started to show a steady climb in human deaths by 1996. By 2005, death rates were higher by about 1.4 deaths per 1,000 people in some districts. All in all, the regions with crashed vulture populations “saw an increase in human all-cause death rates of at least 4.7 per cent, averaged over 2000 to 2005.” So the deaths of 50 million vultures precipitated the deaths of approximately 500,000 people. And that’s what made the news.

The economists concluded that “vulture collapse in India provides a particularly stark example of the type of hard-to-reverse and unpredictable costs that must be accounted for when evaluating the introduction of new chemicals into fragile and diverse ecosystems. Although it is easy to be wise after the fact, it is plausible that a counterfactual policy regime in India that tested chemicals for their toxicity to at least keystone species might have avoided the collapse of vultures.”

None of this is news, unfortunately. The near extermination of the bison created a health crisis for Indigenous people on the Great Plains that echoes to this day. Chief Crow Plenty-Coups expressed his grief: “But when the buffalo went away the hearts of my people fell to the ground, and they could not lift them up again.”

Years ago the U.S. ecologist Garrett Hardin coined the first law of ecology: "We can never merely do one thing.” It didn’t tell us what to look for but advised that we examine every intervention into the natural world with prudence. Hardin even proposed a sort of check list for thinking about the effects of new chemicals, gadgets and “developments."

His filter, which echoed of ancient wisdom, proposed that we first consider the words, then the numbers and, finally the consequences.

Hardin’s filter asked “if the best words have been used, if quantities have been duly considered, and if the consequences of time and repetition have been taken into account.” How eloquent is that?

But an ecological check list is by nature both subversive and conservative. It would retard progress, and that’s why corporations and politicians reject its adoption let alone its discussion. So the essential transition that modern civilization really needs at this moment of extinctions, continues to be flouted or ignored.

The political scientist and ecologist William Ophuls has explained our general aversion to ecological thinking. He writes that “Human ecology is against the conquest of nature; against growth as we think of it; against the isolation of thought and action; against individualism as an ideology; and against moral absolutes like the inalienable rights of man.” Such thinking “demands only that our current political, social, economic and moral order be stood on its head.” So why would we want to go there?

The company that made diclofanec has a long history. Its parent company, Geigy, synthesized the pesticide DDT in 1938 and patented the remarkable mosquito killer in 1940. Marketers sold DDT as magic solution to disease control.

In 1962 Rachel Carson wrote Silent Spring. It remains a pioneering critique of modernity that detailed the biological consequences of widespread application of DDT for eagles, falcons, fish and even children.

At the time Carson asked a brave question, and it remains an essential one. “Have we fallen into a mesmerized state that makes us accept as inevitable that which is inferior or detrimental, as though having lost the will or the vision to demand that which is good?”

The near extinction of India’s vultures has posed that question yet again.