Vultures

The bird’s wings were huge, nearly seven feet in span and broad, so broad

that when it landed and tucked them away it was almost like a conjuring

trick. Having thus folded itself up it lurched forward, swaying from side to

side, its shoulders hunched and its naked “S” shaped neck bent down, hooked

beak catching the sun as it tilted its head thirty degrees this way, and

then thirty degrees back again. It moved sideways along the back of the

buffalo, sidling like a pigeon on a wire. But here the pigeon comparison

ended, for having reached the gaping hole in the side of the animal, it

plunged its whole head into the rank mass of decaying intestines and flesh.

A cloud of flies arose and the head withdrew, covered in gore, the beak

gulping, the throat working. Sometime later, replete, the bird flew heavily

to a leafless branch a few feet above the ground and paused to void its

bowels directly down its legs and over its feet. Perhaps a measure designed

to cool the bird, it seemed to me the final touch to a rather disgusting

piece of nature’s handiwork. If I had been a witness to a Zoroastrian “sky

burial” where Indian vultures are invited to Parsee funerals and reduce a

dead human to a “purer state” by consuming it entirely, aided somewhat by a

priest’s butchering of the corpse and pulverizing of the bones, I would have

added the emotionally confusing element of the food subject to my feelings.

As it was I still had to look away in disgust. It is easy to see why the

birds have been assigned the mythological role of gatekeepers to hell,

described as “abominations among fowls” in the bible and used as symbols for

any disgusting or gruesome consumption in literature and the press. 

It isn’t easy to watch a vulture feed and it isn’t pleasant to even describe

an activity that can quickly and effectively reduce the carcass of a bloated

water buffalo to bare, dry bones. Tens of millions of vultures used to

provide this necessary service in countries such as India, Pakistan and

Nepal. They consumed sacred cows, household garbage and dead animals of all

sorts, paying scant regard to the state of putrefaction of the corpse they

consumed. In this way they tidied up even diseased carcasses and amazingly

were able swallow the microbes responsible for botulism, cholera and

anthrax. The vulture’s remarkable gastrointestinal tract can deal with

extraordinary horrors. Vultures have always provided this essential service

on the Indian subcontinent, and their job has only become more important as

the population has erupted to exceed 1.7 billion people (2015) and their waste. 

 So it is alarming to discover that in a period of only a few years this

once vast population of carrion feeders has crashed dramatically from more

than eighty million birds to a few more than a thousand. It is quite likely

that three species of vulture, the long-billed, the white-backed and the

gryphon, will be extinct in the very near future. What has been the cause of

this ecological catastrophe? What will be its impact on the ecosystem? Is

there action that can be taken to save the birds so that they can continue

to provide their grim but essential service? There are now some answers to

these questions, but answers in this instance do not provide an obvious

solution. 

         The precipitous decline of the vultures escalated quickly during

the 1990s and by 1997 it was clear that the three species were threatened by

a devastating blight of some sort. It was first assumed that a disease was

responsible and viruses were high on the list of suspects. Perhaps some form

of avian flu or a West Nile type virus was at work? In 2000, the Peregrine

Fund focused on the problem, initiating the Asian Vulture Crisis Project

with the Ornithological Society of Pakistan. Study sites were established

and in the ensuing three years, hard evidence was gathered documenting the

vulture’s swift decline. Autopsies of dead birds showed evidence of renal

failure and gout. Gout in humans is a disease often associated with rich

living and over consumption of red meat, brains, kidneys, liver or heart,

especially from cows. Ironically a somewhat vulture-like diet! A metabolic

malfunction causes uric acid levels in the blood to elevate and the

subsequent deposition of crystals of this substance causes an arthritic pain

in the joints, most often in the big toe. The digestion of protein results

in amino acids which are of course, essential dietary components used to

build the body’s own protein. Animals are unable to store amino acids the

way they can store fats and sugars, so excess amino acids must be further

digested and their toxic nitrogenous fraction eliminated. This is most

simply done with the release of ammonia. Ammonia is, however, extremely

poisonous and this method of getting rid of nitrogenous waste is only

possible with fish, where their environment quickly dilutes the noxious

waste. Mammals have modified the process to produce urea, a still poisonous

molecule that is carefully stored as urine in the bladder. Birds and

reptiles, careful to conserve water, produce uric acid, a crystalline solid

that makes up part of what they excreted. It is perfectly normal for

vultures to produce uric acid; the problem arises when the kidneys are

unable to get rid of it. Autopsies of stricken vultures revealed their

internal organs to be covered with this white pasty substance.  Death was

rapid. The vultures died while still looking healthy and with no overt signs

of wasting and no obvious infection. A vulture would return to its nest site

and assume a droop-necked posture that was soon recognized as an indication

that the end was near. Post mortem analyses provided few clues beyond the

uric acid and kidney failure, signs that often indicate poisoning. In the

three years it took to discover the cause, the population was drastically

reduced to a few thousand birds. 

Indian beasts of burden work hard to plough fields, pull carts, carry heavy

loads and struggle with the problems of a third world economy. When they are

unable to work, having become lame or are otherwise in pain, a magic

veterinarian drug called diclofenac proved to act as an anti-inflammatory

agent, effecting the “cure” that put the beasts back in harness. The drug

was cheap, easily available and so widely used. Diclofenac was originally

designed for human use where it is also effective as an anti-inflammatory

agent, but for birds it has proved fatal. The amount of the drug required to

kill a vulture turns out to be remarkably small. Oxen, cows and buffalos

were given the drug, and the vultures, ultimately consuming the carcasses,

died within a few weeks. 

         Extinctions understandably often provoke a public outcry in

America. A threatened butterfly or tiny fish can galvanize public opinion

and concern. Developers, attempting to put economics before a length of

unique DNA, can become the targets of contempt and demonstrations. In North

America a species that is no longer able to hold its own is most often a

victim of habitat destruction, as our growing population either

expands to occupy new territory or pollutes an existing developed area.

Overpopulation is bound to have an impact on our ecosystems, but consider

the effects of a population more than five times the size of ours, crowded

into an area one third the size of the U.S. Many animals and plants are

either threatened or have already become extinct on the Indian subcontinent,

but the rapid demise of the vultures is remarkable and especially

frightening for reasons that go beyond the finality of extinction. It is the

first time that a drug has found its way into the food web with such

unexpected and disastrous consequences.  The problem highlights the care

that should be taken in the disposal of unwanted pills. Here in North

America every bathroom cupboard is quite possibly a deadly treasure trove of

partially consumed prescriptions whose effects on our environment are

Most often unknown. 

         When vultures consume a dead cow they do so in a way that

efficiently returns the nutrients to the primary producers. They are also

able to dispose of disease causing agents as they clean carcasses. Today in

an India lacking vultures, packs of feral dogs are feeding on these

carcasses, breeding rapidly and spreading diseases, notably rabies.

Decomposition of the cows takes longer without the efficient vultures, and

disease-spreading flies multiply. But perhaps the most insidious aspect is

the effect on the ground water. When fly larvae and bacteria reduce a

carcass, their waste is able to seep into the soil and pollute what is

already a precarious water supply.  The extinction of the vultures can be

expected to have far-reaching affects on India, Pakistan, Bangladesh and

Nepal. 

         Is there a hopeful prognosis? Can the vultures be saved, or has

their population been reduced to a point of no return? Happily the Indian

government has banned the use of the offending drug, and publicity regarding

the devastation of the three vulture species has made other southeast Asian

countries aware of the problem. In America the California Condor has been

bred in captivity with difficulty and released to feed on what they can

find. Their intended food sources such as the vast herds of bison that once

populated the great plains have been hunted nearly to extinction and there

is probably no longer an ecological niche for this bird. In India the role

in the food web for vultures still exists, so if the birds could be bred in

captivity and eventually released into an environment free of diclofenac, it

is possible that the populations might grow and the birds once again provide

their essential service. Captive breeding programs are always difficult, but

in the case of the vultures might be successful. Being carrion eaters,

vultures do not need to be taught to hunt and while they produce only two

eggs a year, given time their numbers would grow. However, even if large

numbers of the birds could be reintroduced in their original habitat at some

point in the future, the program could not be certain of success. The

numbers of vultures have dwindled to a point where the lack of genetic

variation in these new populations would make them extremely vulnerable to

any disease that should rear its head. Breeding programs designed to

reintroduce the cheetah in India and Africa also face this problem. At some

point in the past cheetahs entered a genetic bottleneck when some

catastrophe greatly reduced their numbers. Their gene pool is so inbred and

similar that skin grafts from one animal will grow without rejection on

another. As far as their immune systems are concerned they are all the same

animal! It is variation in the genetic make up of individuals within a

population that provides the basis by which a species is able to withstand

disease and changes that may take place in the environment. You could say

that a species puts its best foot forward and in a sense “tries its best” in

any environmental situation. Reestablishing the vultures from a small number

of individuals will produce a population lacking in this variation. 

         So it isn’t easy to watch an Indian vulture feed for reasons that

go beyond aesthetics and the seemingly sordid nature of their diet. The

problem is that in India there are so few vultures left to watch. The most

recent estimates of the combined total for the three Indian species is

little more than a thousand, and dropping, quickly. Is there somewhere that

blame can be assigned? Did greed, negligence or inaction cause the

extinction of the vultures and the resulting effects on the Indian

countryside and water supply? In many ways it would seem to have been bad

luck. Who would have guessed that small amounts of an anti-inflammatory

drug, so useful in one sphere, could have such a devastating affect in

another area? Is there a lesson to be learned? It already takes a long and

costly time of testing to bring a drug to the marketplace. Can we expect

future testing to extend to all life forms that may be affected? 

My son, in a relaxed teenage moment, once said to me “But dad, shit

happens!” It seemed to me at the time that this was a crude and silly phrase

that invited me to throw up my hands and resign myself to fate. A little

irritated, I replied that, “if you think, plan ahead and pay attention, ‘it’

doesn’t happen nearly as often.” Darwinian change depends on the survival of

the fittest and this law of the jungle will continue to prevail. We may

assign various levels of “worth” to certain species and attempt to

manipulate the environment in favor of those we deem more worthy or useful

or pretty, but in the end nature will sort itself out. Unfortunately this

may not be pleasant for the losers. Tennyson’s “Nature red in tooth and

claw” may be replaced by errors in chemistry, and innovations that benefit

some while inadvertently destroying others. I suppose we may be reduced to

considering my son’s adage, because “shit” does indeed happen, but this

doesn’t mean we shouldn’t  “Try our best.” This is what species do.