The Great Indian Vulture Crisis

The Great Indian Vul­ture Crisis

Sci­en­tists have esti­mated that as recently as the early 1990′s, there were at least thirty mil­lion vul­tures in India and Pak­istan.  They used to fly in flocks so mas­sive, only rough approx­i­ma­tions of their num­bers could be made. Within a mat­ter of a few years, their num­bers started to decline faster than any other avian col­lapse in his­tory.  Researchers pin­pointed the cause of the vul­tures’ demise to kid­ney fail­ure, but had no idea why it was occur­ring.  By 1999, the sit­u­a­tion became so grave that not one pair of vul­tures could be seen together.

Start­ing in late 2001, Dr. J. Lind­say Oaks, Pro­fes­sor of Micro­bi­ol­ogy at Wash­ing­ton State Uni­ver­sity, ran scores of tests on the deceased birds look­ing for viruses, bac­te­ria, heavy metal poi­son­ing, pes­ti­cides and nutri­tional defi­cien­cies to find a cause for their kid­ney fail­ure.  It wasn’t until early 2003 when Oaks decided to look at their food source which was almost entirely domes­tic live­stock, includ­ing cat­tle.  In Hin­duism, the main reli­gion of India, cows are thought to be sacred and it’s against Indian law to kill or cause them pain.  As such, farm­ers would lib­er­ally admin­is­ter a pain killer called diclofenac to ease any suf­fer­ing their cows might endure.  When the cows even­tu­ally died, they would be sent to “car­cass fields” to decom­pose because they couldn’t be buried or cre­mated accord­ing to the same reli­gious rea­sons that shel­tered them from suf­fer­ing or death.

Vul­tures have tra­di­tion­ally played a vital role in the decom­po­si­tion of these car­cass fields by strip­ping the dead cows to the bone. After pour­ing through the data, Oaks dis­cov­ered the vul­tures were dying of kid­ney fail­ure from the accu­mu­lated diclofenac in the cows.  Even after find­ing this out, the Indian gov­ern­ment didn’t ban the drug until 2006. Even five years later, in 2011, the drug is still used in India for vet­eri­nary pur­poses even though safer alter­na­tives exist, mak­ing cer­tain that the num­bers of vul­ture will con­tinue to dwin­dle.  This is just another avian species that is going the way of the dodo or the pas­sen­ger pigeon.

What about con­ser­va­tion efforts?

Con­ser­va­tion­ists con­sider all the South Asian vul­tures to be func­tion­ally extinct because there are not enough of them to sus­tain them­selves.  Cap­tive breed­ing efforts have, at best, been painstak­ingly slow because vul­tures take five years to reach repro­duc­tive matu­rity and when they do, they mate only once a year, pro­duc­ing only one egg.  At that rate it will take decades of cap­tive breed­ing sim­ply to pre­vent the birds from going com­pletely extinct. This sce­nario is rem­i­nis­cent of the Cal­i­for­nia Con­dor cri­sis, where there were only 22 of them left in 1983 and cap­tive breed­ing helped bring their num­bers up into the hun­dreds as of 2011. Sadly, sci­en­tists do not expect any Indian vul­ture born today to be able to sur­vive until matu­rity because of the spo­radic pres­ence of diclofenac in its food source.

What’s the impor­tance of vultures?

Even though vul­tures are some­times looked at in a neg­a­tive light, they play a very impor­tant role in effi­ciently dis­pos­ing of car­casses and dis­in­fect­ing the meat for con­sump­tion.  Their strong stom­ach acid and high body tem­per­a­ture destroy corpse pathogens such as rabies and tuber­cu­lo­sis with lit­tle to no ill effects unlike any other ani­mal.  Their pres­ence may be asso­ci­ated with death but they have qual­i­ties that are admirable when you acknowl­edge their patience in wait­ing and never attack­ing any­thing that is still living.

Who is eat­ing the dead cows now?

While the vul­ture pop­u­la­tion has been dec­i­mated, the feral dog pop­u­la­tion has exploded.  With this new abun­dant source of food, wild dogs have become the new pri­mary scav­enger.  These dogs do not resem­ble the typ­i­cal scrawny, fee­ble image of stray dogs either; they look healthy and strong thanks to their abun­dant food source.

Unfor­tu­nately, the dogs do not pick apart the car­casses as thor­oughly as the vul­tures did, even­tu­ally caus­ing ground water con­t­a­m­i­na­tion.  In addi­tion, their phys­i­ol­ogy isn’t as well-adapted to scav­eng­ing, and instead of destroy­ing dis­eases such as rabies, they sim­ply trans­mit them.  When dogs con­tract rabies, they suf­fer from brain dam­age that makes them become extremely aggres­sive and prone to bite any­thing that comes nearby.  India now has a rabies epi­demic with the high­est rate of human rabies in the world, result­ing in about 35,000 deaths per year.

The dogs prey on the cows, leop­ards prey on the dogs and humans are caught in the middle.

The grow­ing wild dog pop­u­la­tion makes easy prey for indige­nous leop­ards who have begun enter­ing vil­lages and cities to hunt them.  As a result, the leop­ard pop­u­la­tion has also increased dra­mat­i­cally and encoun­ters with humans have been much more fre­quent, result­ing in hun­dreds of fatal­i­ties occur­ring in recent years.

Who else is affected by the vul­tures’ demise?

In India, there is a group of Zoroas­tri­ans called ‘Par­sis’ who don’t believe in cre­ma­tion or the bur­ial of human remains.  Instead, they prac­tice an equiv­a­lent of the Tibetan “sky buri­als”, where the Par­sis lay their dead out for vul­tures to con­sume in a raised struc­ture called a “Tower of Silence.”  Since the vul­tures are too few to take care of the remains as they have done for cen­turies, the Par­sis have begun search­ing for alter­na­tive solu­tions. A series of solar col­lec­tors (mir­rors) were installed in the Tow­ers of Silence to accel­er­ate decom­po­si­tion, though their lim­ited suc­cess has the Par­sis con­sid­er­ing their own con­ser­va­tion project to repop­u­late the dec­i­mated vultures.

This entire chain of events seems unreal, but is indica­tive of just how pow­er­ful our pres­ence on Earth is in actively reshap­ing ecosys­tems, whether we intend to or not.