A Threat to the Lords of the Sky: The Asian Vulture Crisis
Writer’s Comment: The purpose of this paper was to research a subject in raptor biology, synthesize the information, and provide my own perspective on the topic. It is meant for an audience with some passion for the natural world. The word vulture is often coupled with death, disease, and filth. Though these associations are not necessarily incorrect, they are not suggestive of vultures’ beneficial role in our world. Many people do not realize that vultures are not only important to the environment, but to the economy, public health, and culture as well. In this paper, I aimed to give an overview of the Asian Vulture Crisis—a population decline of three vulture species in the Indian sub-continent. Not only is it a topic of great concern for an entire subcontinent, it highlights how integral vultures are in sustaining everyday life. I would like to thank Allen Fish for encouraging us to voice our opinions and for emphasizing that science is not just about reporting the facts, but finding the story in our work.
Instructor’s Comment: Over the last three decades, three vulture species of the Indian subcontinent have crashed to 5% of their historical numbers. This might seem like just another ecological sob story until you consider the role of aerial scavengers in certain Indian and Pakistani religious sects. Parsees have depended on vultures for more than thousands of years as critical and even spiritual agents in the sky burial of human corpses. The massive decline of vulture numbers translates to both slowing the process of decomposition and interrupting the ascension of human souls. Essayist Johanne Boulat expertly explores the nuances of this deep-rooted loss of species, from the recent discovery of the poison attacking the vultures to the unprecedented cross-cooperation of western and eastern bird experts striving to correct the damage. Though the crisis is still being resolved, Boulat’s story carries a beam of hope that we are capable of responding swiftly and intelligently—even across religious and political boundaries—to save species.
—Allen Fish, Department of Animal Science
The vultures of the Indian subcontinent are revered for their role as recyclers of the substances of life. They thrived for millennia in the region, but despite their status as symbols of devotion, they are now in danger of extinction. Over the past fifteen years, Indian sub-continent populations of three Old World vulture species have crashed, and now all three are listed as critically endangered by the International Union for the Conservation of Nature (IUCN) (Lu et al. 2009). After extensive investigation, researchers have discovered the source of the population crashes: a veterinary anti-inflammatory drug called diclofenac (Oaks et al. 2004).
The survival of vulture species is not all that is at stake. Because of the vultures’ role in carrion removal, their declines have ecological, economic, public health, and cultural implications (Pain et al. 2008). Vultures are keystone species on the Indian subcontinent and must be a priority in conservation efforts (Peregrine Fund 2010). To illustrate the need for conservation, I will briefly describe the vultures themselves and provide detail on the history of vulture populations and research in the Indian subcontinent. I will highlight the wide range of vulture services to the planet, and describe current and future plans to save these species.
The three critically endangered species of the Indian subcontinent are the Oriental White-backed Vulture Gyps bengalensis (OWBV), the Long-billed Vulture G. indicus (LBV), and the Slender-billed Vulture G. tenuirostris (SBV) (Pain et al. 2008). Part of the Accipitridae family, the Gyps genus is composed of eight Old World species living in Asia, Europe, and Africa, filling the soaring and scavenging raptor niche for the Indian subcontinent (Pain et al. 2003; Peregrine Fund 2010). Ecologists believe Gyps species evolved in parallel with large ungulate herds, as they primarily feed on the tissues of large mammal carcasses. Wild ungulates are no longer abundant, but farming practices have provided vultures with ample carrion. Gyps species are social birds, tending to feed communally - even between species - and to nest colonially (Pain et al. 2003). They are long-lived, generally taking five years to reach maturity and laying a single egg per breeding season, which makes their recovery all the more challenging (Peregrine Fund 2010).
The magnitude and speed of the vulture declines that began roughly three decades ago on the Indian subcontinent initially baffled scientists and spurred a frantic search for the source of the problem. In the first half of the 20th century all three of the now critically endangered species were considered abundant in Southeast Asia. In northern and central India where the slaughter of cows is prohibited due to religious beliefs, cow carcasses have satiated vultures for centuries. In fact, during the 1970s there were so many vultures at carcasses that they were considered a hazard to aircrafts (Pain et al. 2003). However, by the end of the century, sick and dying birds were reported across the Indian subcontinent (Pain et al. 2003). Lethargy and drooping necks were the primary symptoms.
Between the mid 1980s and late 1990s, counts in Keoladeo National Park, located in the northern Indian state of Rajasthan, indicated a 95 percent decline in numbers of OWBVs and LBVs (Pain et al. 2003). In 1991, Dr. Vibhu Prakash, the Principal Scientist of the Bombay Natural History Society, began quantifying the vulture declines by conducting road transect surveys with his team. Prakash still monitors vulture populations across northern and central India today (Vulture Rescue 2010). In India, Pakistan, and Nepal, high mortality and low breeding success were both identified as causes of vulture population declines (Pain et al. 2003).
In August 1999, a conference analogous to one held 34 years earlier in Madison, Wisconsin in response to the disappearance of Peregrine Falcons in the Eastern United States, was held in Mumbai by the director of the Bombay Natural History Society, Asad Rahmani, to address the vulture crisis (Risebrough 2004). Speculations as to the source of the problem included food shortages, persecution by locals, contaminants, and disease (Pain et al. 2003). Food shortages were attributed to overhunting of wild ungulate herds and changes in raising practices of domestic stock (Srikosamatara and Suteethorn 1995). Both of these were believed to be contributors to a decline in carcass numbers (Cambodian Wetland Team 2001). Support for this view came from Cambodia where the biggest relict populations of Gyps vultures and wild ungulate herds persist and where locals still practice free-ranging of domestic animals (Pain et al. 2003). Despite these clues, vulture necropsies indicated that starvation was not a major cause of death (Gilbert et al. 2002; Prakash et al. 2003). Persecution by local people was quickly ruled out because vultures are valued in cultures across the Indian subcontinent. For instance, members of the Parsee faith and Buddhists of the Tibetan plateau depend on vultures to dispose of their dead, and Hindus worship Jatayu, a vulture saint who is featured in the Hindu epic Ramayana (Pain et al. 2003; Chatterjee 1993). The two sources of vulture declines thought most likely were toxic contaminants and disease, because both of these predict patterns of mortality that matched the speed and pervasiveness of vulture deaths seen across the Indian subcontinent (Pain et al. 2003).
In 2000, the Peregrine Fund began research on vultures in Pakistan, while the Bombay Natural History Society continued work in India (Risebrough 2004). Although pesticide use on the whole showed decline through the 1990s, scientists suggested that these statistics have masked trends in individual chemicals. In 2001, Dr. J. Lindsay Oaks and his team from Washington State University, working for the Peregrine Fund, found kidney failure to be the cause of visceral gout in dead birds (Pain et al. 2003). Visceral gout leads to a buildup of white deposits of uric acids on the surface of organs, ultimately leading to the bird’s death (Peregrine Fund 2010). The cause of the gout was determined by testing dead vultures for environmental pollutants, including pesticides, heavy metals, and herbicides (Vulture Rescue 2010). Some of these compounds were found in the birds, but in amounts too low to cause physiological damage and showing no link to the visceral gout (Vulture Rescue 2010).
In 2003, akin to the discovery of DDT as the source of Peregrine extinction in the eastern United States in 1969, Oaks and his team found the vultures were being poisoned (Risebrough 2004). Oaks knew from previous research that Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) had been linked to kidney failure when given to birds. With this in mind, Oaks and his team scoured the pharmaceutical shops in Pakistan. They found a new NSAID on sale–the veterinary drug diclofenac (Vulture Rescue 2010). Diclofenac is a painkiller and anti-inflammatory drug used as medicine for domestic livestock and it is toxic to vultures. Dead birds with visceral gout were tested for NSAID poisoning and all were found to contain traces of diclofenac (Oaks et al. 2004). To back their claim that diclofenac was indeed the perpetrator, Lindsay’s team gave diclofenac to captive vultures. As predicted, these birds died of visceral gout (Vulture Rescue 2010). Subsequent research conducted by other groups confirmed Lindsay and his team’s results (Vulture Rescue 2010).
In light of all the evidence, India, Nepal, and Pakistan banned diclofenac in 2006 (Peregrine Fund 2010). But although the drug is no longer legal, it is still in circulation. Monitoring by the Peregrine Fund (2010) shows OWBV, SBV, and LBV populations are still declining. In India, OWBV populations have declined by an astonishing 99.7% since 1990. The numbers are certainly not reassuring in terms of the vultures themselves, and even more frightening perhaps is that vulture survival is not the only thing at stake.
The vultures of the Indian subcontinent play a critical role in their surrounding environments, economies, and cultures. A direct and visible impact of their decline is that carrion is left to rot and carcasses are left uncleaned. Cleaning of carcasses by vultures is believed to eliminate bacteria and prevent disease. Additionally, the clean bones left over after vultures feed are picked up by India’s poor and used as fertilizer (Pain et al. 2003). Even in areas where feral dogs feed at carcasses, the dogs: (1) only eat certain tissues; (2) do not clean the bones as well as vultures do; and (3) are known to attack humans (Pain et al. 2003). Moreover, feral dog and rat populations have increased in India due to the surplus carrion. In 2005, feral dog populations were estimated to number in the 30 millions, as compared to only 17 to 18 million in 1980 (Vulture Rescue 2010). This increases predation on some wildlife, and it also poses a disease threat to both wildlife and humans. India has the highest rate of rabies in the world and, as vulture populations of OWBVs, SBVs, and LBVs have declined, the disease has spread. Scientists also think increases in non-vulture scavengers augment the risk of anthrax and tuberculosis (Vulture Rescue 2010).
Culturally, vultures are important in the sky burials of several faiths–a practice that involves leaving bodies out in the open to be eaten and cleaned by scavengers. This practice may at first seem gruesome to Westerners, as it did to me. But I have come to see it as a sensible way to return our bodies to the earth. Once we die–regardless of whether or not we believe in an afterlife–we no longer need our bodies. Giving human bodies to scavengers is a way of recycling the matter that flows through us in our lives and, ultimately, through all life. From the perspective of a food web, when we eat meat, are we not doing the same thing? Simply put, I can see the appeal of this practice as a way of letting go of one’s body and all that is material, and giving oneself to the flow that connects all living beings.
That being said, Hindus, Buddhists, and Parsees all use sky burials as a funerary service (Baral and Gautam 2007). In some places, such as at high altitudes on the Tibetan plateau, the practice is not just spiritually, but ecologically necessary. Due to the extreme cold, the bodies would not otherwise decompose (Lu et al. 2009). Parsees use sky burials because they believe that fire, earth, and water are sacred and should not be contaminated with corpses (Pain et al. 2003). Instead of burial, they build circular raised structures called “towers of silence” that limit corpse access to airborne scavengers such as vultures (Pain et al. 2003). However, today, Parsees are left with the dilemma of how to dispose of their dead without vultures and without violating the tenets of their religion (Subramanian 2010). Currently solar panels installed on the towers focus sunlight onto the corpses in order to speed up the decay process. This method avoids the use of fire (which is sacred), but it is not as effective as vultures.
Most Parsi priests tend to disagree with modernizing burial methods, but some Parsees believe the faith should adapt in the face of changing conditions (Subramanian 2010). For instance, Dhan Baria, a Parsi woman, is an advocate for modernization (Subramanian 2010). Her mother died in 2006 and was placed on a tower with solar panels, but Baria heard rumors about a growing accumulation of bodies that were not decaying, so she hired a photographer to sneak into the towers. His macabre photographs confirmed the rumors. Because of this, Baria and other Parsees believe that their faith should allow alternative funerary methods, such as cremation and burial (Meera 2010). This example illustrates how deep the implications of vulture declines are—effects are felt not only in the immediate environment but even in the foundations of certain faiths. There are both visible and invisible consequences. To me, this means that to study vultures, we cannot isolate them but must examine them in many contexts.
The religions mentioned above all advocate for the conservation of vultures because they see them as spiritual beings (Pain et al. 2008). Although these beliefs are integral for the preservation of vulture species, they must be accompanied by action. I propose five means of conserving vultures: a phase-out of the drug diclofenac, a captive breeding program, vulture population monitoring, education that incorporates citizen involvement, and continued research.
It is imperative for the conservation of the Gyps vultures that diclofenac be phased out and that a substitute is found (Peregrine Fund 2010). A likely candidate is Meloxicam, which tests indicate has low toxicity for vultures as well as other raptors and scavenging birds (Pain et al. 2008). Meloxicam has already been exchanged for diclofenac in areas around Chitwan National Park in Nepal, and workshops are held there to educate farmers about the dangers of diclofenac (Vulture Declines 2010).
Another important approach to conservation is captive breeding. So far, LBVs bred in captivity by the Peregrine Fund have produced three chicks that hatched in February and March of 2010 and fledged by June. Other breeding centers in India have produced OWBVs and SBVs. However, since diclofenac is still present in the environment in large doses, none of the fledglings have been released into the wild (Peregrine Fund 2010).
A key player in the conservation of the Gyps vultures is the organization Vulture Rescue, a collaboration of conservation and research groups (including the Peregrine Fund and Bombay Natural History Society). In addition to running captive breeding centers, Vulture Rescue helps monitor vulture populations using counts and satellite-tracking, conducts research on drugs, and creates “Vulture Safe Zones.” These zones are areas of low diclofenac toxicity where the small, remaining wild populations of vultures can be preserved (Vulture Rescue 2010). Finally, an advocacy program helps educate the public about what they can do and why vultures are critical to everyone’s wellbeing (Vulture Rescue 2010).
The need for education and citizen involvement was highlighted in a 2004 survey conducted by Bird Conservation International. Randomly selected households in the Rampur Valley of Nepal were surveyed for their attitudes and actions towards vultures. Although 78% of those surveyed had favorable attitudes toward vulture conservation, their actions were often detrimental to vultures. For instance, Kapok trees, the main roosting and nesting substrates for vultures, were logged in one area to build a community school. Local actions such as these can have serious impacts on vulture breeding since OWBV, LBV, and SBV populations are already so small and individuals lay only a single egg per breeding season. Furthermore, this example underlines one of the main problems with conservation efforts: people like the idea of conservation, but the demands of conservation often conflict with their basic needs (Baral and Guatam 2007). The solution I see as most promising for this problem is not only to educate people about the problem but also to involve them directly in conservation so that they see its benefits and profit from it. For instance, many tourists are interested in seeing Asian vultures. The money gained from tourism can be used as an incentive for locals to preserve these birds (Vulture Rescue 2010).
The final part of the conservation plan involves monitoring related species such as the Himalayan Griffon, G. himalayensis, of the Tibetan Plateau (Lu et al. 2009). Although only OWBVs, LBVs, and SBVs are listed as endangered on the Indian subcontinent, experiments on captive birds suggest that all Gyps vultures are susceptible to the effects of diclofenac (Virani et al. 2008). The earlier a population is monitored, the easier it will be to prevent poisoning, and the faster conservation groups can respond in case something does go wrong (Lu et al. 2009). So far, surveys indicate that Himalayan Griffon populations are stable, but because of how geographically close they are to diclofenac sources, they are still at risk (Lu et al. 2009).
The best way to approach conservation is with the three-headed beast of research, education, and action. Conservation will only work if it is multi-faceted. For instance, captive breeding cannot work without research on the species’ behavior, development, and reproductive needs. Nor can it work without support from the public and restoration of the release habitats.
The most challenging part of the Asian vulture crisis is how to encourage people to use another drug on their cattle, or to use no drugs at all. Clearly, making something illegal doesn’t remove it from circulation. Regulations can be put in place, but to truly effect change, education is necessary, and the best way to educate people is through involvement. History shows us that this problem is not an impossible one to solve. Many species were on the brink of extinction due to DDT, but all have rebounded. Other success stories include the return of the Peregrine Falcon and the California Condor.
Something else I believe to be essential to conservation is information-sharing in the scientific world. For instance, when Dr. Oaks and his colleagues discovered that diclofenac was killing the vultures in the Punjab province of Pakistan, they shared their preliminary findings before publication. This helped speed up the process of testing other vulture populations for diclofenac poisoning, which in turn helped speed up the banning of diclofenac (Pain. et al. 2008).
The Asian vulture crisis is an incredible, modern case in point of the famous John Muir quote: “When we try to pick out anything by itself, we find it hitched to everything else in the universe.” By themselves these vultures are just scavengers. But of course, nothing is ever by itself. In the context of the Indian subcontinent, vultures are the center of the spider web, where all threads of life eventually converge. They are the ones who do the “dirty work” and the housekeeping–functions that seem unpleasant to us, but that are essential to ecological, economic, and spiritual health. Hence, the dramatic decline in vultures is not simply a risk of extinction for three species, but a risk for the balance of the entire Indian subcontinent. Is it worth the effort and the money to save them? Can we provide substitutes for their services? Perhaps. Humans have always shown ingenuity in the face of catastrophe. But I think that even beyond their keystone roles, there is something regal about these birds. It would be a pity to lose the Lords of the Sky.
Baral, N., and R. Gautam. 2007. Socio-economic perspectives on the conservation of critically endangered vultures in South Asia: an empirical study from Nepal. Bird Conservation International 17: 131-139.
Cambodian Wetland Team. 2001. Final report on participatory rural appraisal in Boung Rei village, Sambo District, Kratie Province, Mekong River. Royal Government of Cambodia, Inventory and Management of Cambodian Wetlands Project (MRC–Danida), Phnom Penh.
Chatterjee, D. 1993. The Elephant-headed God and Other Hindu Tales. Calcutta: Rupa.
Gilbert, M., M.Z. Virani, R.T. Watson, J.L. Oaks, P.C. Benson, A.A. Khan, S. Ahmed, J. Chaudhry, M. Arshad, S. Mahmood, and Q.A. Shah. 2002. Breeding and mortality of Oriental White-backed Vulture Gyps bengalensis in Punjab Province, Pakistan. Bird Conservation International. 12: 311–326.
Lu, X., D. Ke, X. Zeng, G. Gong, and R. Ci. 2009. Status, ecology, and conservation of the Himalayan Griffon Gyps himalayensis (Aves, Accipitridae) in the Tibetan Plateau. Journal of the Human Environment. 38(3):166-173.
Pain, D.J., C.G.R. Bowden, A.A.Cunningham, R. Cuthbert, D. Das, M. Gilbert, R.D. Jakati, Y. Jhala, A. Khan, V. Naidoo, J.L. Oaks, J. Parry- Jones, VI. Prakash, A. Rahmani, S. P. Ranade, H. Sagar Baral, K. Senacha, S.
Saravanan, G. Swan, D. Swarup, M.A. Taggart, R.T. Watson, M.Z. Virani, K. Wolter, and R.E. Green. 2008. The race to prevent the extinction of South Asian vultures. Bird Conservation International. 18: 30-48.
Pain, D.J., A.A. Cunningham, P.F. Donald, J.W. Duckworth, D.C. Houston, T. Katzner, J. Parry-Jones, C. Poole, V. Prakash, P. Round, and R. Timmins. 2003. Causes and effects of temporospatial declines of Gyps Vultures in Asia. Conservation Biology. 17: 661-671.
Peregrine Fund. 2010. Asian Vulture Crisis–Conservation Projects. http://peregrinefund.org/conserve_category.asp?category=Asian%20Vulture%.... Examined February 6, 2011.
Prakash, V., D.J. Pain, A.A. Cunningham, P.F. Donald, N. Prakash, A. Verma, R. Gargi, S. Sivakumar, and A.R. Rahmani. 2003. Catastrophic collapse of Indian white-backed Gyps bengalensis and long-billed Gyps indicus vulture populations. Biological Conservation 109: 381–390
Oaks, J.L., M. Gilbert, M.Z. Virani, R.T. Watson, C.U. Meteyers, B.A. Rideout, H.L. Shivaprasad, S. Ahmed, M.J.I. Chaudhry, M. Arshad, S. Mahmood, A. Ali, and A.A. Khan. 2004. Diclofenac residues as the cause of vulture population decline in Pakistan. Nature. 427: 630-633.
Risebrough, R. 2004. Fatal medicine for vultures. Nature. 427: 596-598.
Srikosamatara, S., and V. Suteethorn. 1995. Populations of Gaur and Banteng and their management in Thailand. Natural History Bulletin of the Siam Society 43: 55–83.
Subramanian, M. 2010. “A Crisis for the Faithful.” The Wall Street Journal 30 April 2010.
Virani, M.Z., J.B. Giri, R.T. Watson, and H.S. Baral. 2008. Surveys of Himalayan Vultures (Gyps himalayensis) in the Annapurna Conservation Area, Mustang, Nepal. Journal of Raptor Research. 42: 197-203.Vulture Rescue. 2010. http://www.vulturedeclines.org/. Examined February 26, 2011.