What's eating the vulture?

What's eating the vulture?

Flight into obllivion
The vulture is disappearing in India. Nobody knows why. Some experts blame pesticides

O n october 3, 1998, the Centre For Science and Environment ( cse ), New Delhi, received a letter from Asad R Rahmani, director, Bombay Natural History Society ( bnhs ), Mumbai, mentioning a drastic decline in the vulture population of the Keoladeo National Park in Bharatpur. Rahmani wrote how, within a short span, the number of vultures in the region dropped from 2,000 to just four. He cited observations of his colleague Vibhu Prakash, senior scientist at bnhs 's research station in Bharatpur, who says in the 1980s it was natural to find as many as 350 vulture nests in Bharatpur. But in 1998, Prakash found only four. Sudden declines in bird population is not new for Bharatpur. Between 1987 and 1990, says a bnhs report, some 18 sarus cranes and over 50 ring doves were found dead in the region. More birds dying within the park premises is also a strong possibility. cse sent its environmental toxicologist Amit Nair to Bharatpur to collect samples of animal carcasses -- vultures' primary food source. In 1990, Nair had analysed vulture tissue samples for pesticides and found 0.485 parts per million (ppm) of dichloro diphenyl trichloroethane ( ddt ) and 0.061 ppm of hexachloro cyclohexane ( hch or bhc ) in the birds' bodies. This time, eight carcass samples were sent for analysis to the Facility for Ecological and Analytical Testing at the Indian Institute of Technology, Kanpur. All samples had high levels of ddt and bhc (see box: Poison in plenty ). Many experts and ornithologists believe that such pesticides may be to blame for the fall in Bharatpur's vulture population.

However, some villagers in Bharatpur allege that the Muslim community is poisoning cattle for their hide. There seems to be little truth in these allegations. Traces of bhc have been found in the carcasses. bhc, till 1997, was legally used for agriculture. Villagers in the area cultivate mustard using large quantities of pesticides. Mustard cake is used as a cattlefeed. Also if the Muslims were indeed poisoning cattle on a large scale, there would have been a riot in Rajasthan. Therefore, deliberate poisoning of cattle on a mass scale seems improbable.

Ornithologists have reported dwindling vulture populations in other Asian countries such as Laos, Cambodia, Vietnam and Thailand, too. "There have been reports that cattle carcasses are now being left unattended (in these countries) due to the absence of vultures," writes Rahmani in his note on decreasing vulture population. Though Vietnam and Thailand banned the use of ddt, hexacyclochlorohexane ( hch), aldrin and other such organochlorine pesticides in 1992 and 1996 respectively, these are still being used there and in the neighbouring countries, including Laos and Cambodia. In India, absence of baseline data makes assessments of such population declines next to impossible, he adds.

There can be several factors behind avian population decline, such as habitat destruction, epidemics, hunting, trapping and the occasional food shortage. None of these could be responsible for such drastic declines as witnessed in Bharatpur, and are secondary causes, believe ornithologists. "Pesticides are probably responsible for the recent decline in vulture and other bird populations in India," says Nair. Residues found in the brain tissues of dead birds indicate that these chemicals could indeed be the killers.

So there is reason to believe that there could be a strong link indeed between pesticides and dwindling vulture populations. Vultures, other birds of prey and humans depend on meat as one of their food sources. So if pesticides are affecting vultures through dead animals, they could get to humans, too. But how do pesticides, sprayed on agricultural fields, affect vultures?And how are humans at risk? The answer, explains Tariq Aziz of the wwf- India, lies in the food chain.

"The food chain is a mode for carrying not only food but also pesticides," he says. "Pesticides find their way into the water where they affect the lower-level organisms. Then, as these are devoured by the other creatures, the chemicals affect them too," Aziz continues. "Intake and effects of the chemicals increase several times along the food chain. Assuming a fish's daily diet is a million planktons -- each already contaminated by pesticides in the water. Now if a human or a bird eats some four-odd fish a day, it will definitely have more of the poison."

Is this decline in vultures an ominous sign? Are these birds like the canaries kept by the 19th century miners? Back then, coal miners would not enter the mines unless they had a canary with them. If the mines had methane inside, the bird would succumb first and the men knew it was time to run. Perhaps, there is a similar message for us in the recent vulture deaths.

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The Silent killer

T he pesticide threat first emerged in the West, the us in particular. In the early 1930s, the Dutch elm disease spread across the us. A fungus disease spread by beetles, it proved fatal to trees, blocking their water-conducting vessels. In 1954, us farmers began spraying ddt to kill the beetles in a bid to curb the disease. But the pesticide soon affected robins, killing thousands of birds.

Then, in 1963, came Silent Spring , a landmark book by environmentalist Rachel Carson, which detailed how increased pesticide use affected bird population in the us , sometimes wiping out entire population and even species. Her emotive assessment of the situation -- how birds no longer heralded the onset of spring -- rang alarm bells across the nation. Many conservation measures were suggested and some adopted to ensure spring the welcome it has always enjoyed -- birds returning home after spending their winters in warmer locales. But these have not been enough. Though a few pesticides, such as ddt , dieldrin and chlordane, have been banned by the us and several European nations, the developing world is still at risk as these chemicals still enjoy widespread applications in these parts. India, for instance, has always persisted in using these deadly pesticides such as ddt even in its 'so-called' health programmes.

Toxins in the air...
Among the chemicals usually used as pesticides, organochlorines, including ddt, hch , aldrin, dieldrin, chlordane, are proven killers. ddt and dieldrin are the most dangerous because of their subtle and widespread effects on birds and the so-called 'benefits' they confer on human food supplies. To add to the problem, ddt, dieldrin and chlordane also belong to a class of chemicals called endocrine disrupters. These disrupt development of the immune, nervous and endocrine systems and are of serious concern as they affect cellular and molecular processes that regulate developmental, endocrine and immunological functions. Many of these even mimic and interfere with male and female hormones, modifying development and reproduction.

Throughout the late 1950s and the 1960s, us scientists experimented with ddt. These experiments indicated that when juvenile roosters were injected with the chemical, it led to reduced size of the male genitals (testis) and induced female appearance. In birds, ddt compounds may affect embryonic development by reducing egg shell thickness, as in the case of ducks, or by direct effects on the embryos. When eggs of Californian gulls ( Larus californicus ) and western gulls ( Larus occidentalis ) were injected with methoxychlor and ddt , these caused feminisation of male embryos. Endocrine disrupters also change mating and parenting behaviours in birds, say experts. Birds often eliminate organochlorines and heavy metals by sequestering them in their eggs, a phenomenon that, as mentioned, jeopardises the developing embryos. During the egg-laying period, the eggs receive half of the contaminants that are in the females' bodies (see cartoon: Dark duck tales ).

Moreover, ddt and its breakdown products, classified as Persistent Organic Pollutants ( pop s), are chemicals that take hundreds of years to disappear from the environment. These have even found their way to the polar regions borne by winds. They have caused serious health problems in human, bird and animal populations. Early leakage that might have contaminated land will continue to be a major threat for many years from now.

Organochlorines are severely detrimental to the survival and reproduction of wildlife, especially that of birds such as vultures, which are often indicate contamination in the environment. The first to get affected by the chemicals are vultures and other birds of prey, being on the top of food chain. Barbara Rutherford, policy coordinator, Water Pollution and Toxics at the Switzerland-based wwf international, once assessed the pesticide threat as "one of the great difficulties in identifying exactly how these chemicals (endocrine disrupters and other pesticides) affect birds, animals and humans is that the pattern of effects varies between species and compounds". "General conclusions can be drawn, however," she adds, "even one very low dose of an endocrine disrupter at a crucial stage in the development of an embryo is sufficient to cause irreparable damage." Further, Rutherford points out that the effects are transgenerational -- the gap between intake and effects could be as large as two generations.

...and within us
Studies conducted in Sweden, Canada and the us revealed a strong link between the incidence of a certain type of cancer called Non-Hodgkin's Lymphomas ( nhl ) and the use of pesticides. In Sweden for instance, frequent use of herbicides, such as 2,4-dichlorophenoxyacetic (2,4- d ) has been estimated to increase the risk of contracting nhl by 200-800 per cent.

According to N K Mehrotra, who was with the Industrial Toxicology Research Centre ( itrc ) in Lucknow, India, organochlorines such as toxaphene, hch , strobane, dieldrin and ddt are all known to cause lymphatic cancer in rats and mice, and most certainly in humans, too. Distressingly, these affect both birds and humans through the same channels: vector control, residues in food and in the environment.

In India, there is ample evidence that pesticides have affected birds and humans alike. And most Indians already have these chemicals inside them. A 1993 study conducted by the Indian Council of Medical Research ( icmr ) found alarming levels of pesticide in some 2,205 cow and buffalo milk samples collected from 12 states over a period of seven years ( Down To Earth , Vol 5, No 13). Detectable residues of alpha, beta and gamma isomers of hch -- or bhc , a pesticide known for its extreme toxicity -- were found in 87, 85 and 85 per cent of the samples respectively (See box: Fatal food ). The percentage of samples exceeding the scientifically-approved tolerance limits were 21, 24 and 28 in the case of alpha-, beta- and gamma- hch , respectively. The worst contamination was detected in samples of Andhra Pradesh ( ap ), Bihar and Uttar Pradesh. Dietary intake of beta- hch was about twice the acceptable daily intake ( adi ) among the high-income urban population in ap . ddt residues were detected in about 82 per cent of the samples. Some 37 per cent had ddt traces above the tolerance limit. Maximum levels of ddt residues were found to be 44 times the tolerance limit. States that recorded the maximum ddt levels were Maharashtra, with 74 per cent samples above the tolerance limit, Gujarat, with 70 per cent, ap, with 57 per cent, Himachal Pradesh, with 56 per cent and Punjab, with 51 per cent.

Even infant milk formula and bottled milk had pesticide residues. Of some 186 samples of 20 commercial brands of infant milk formula available in the market, 70 per cent showed ddt contamination and 90 per cent had hch -isomers. The results are frightening: children fed on instant formula would absorb quantities of beta- hch that are 90 per cent more than the adi .

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Chemical catastrophe

Pesticides are essentially products of urbanisation and agricultural modernisation. As cities began growing, lands -- once home to birds -- were put to intensive agricultural use. To increase crop yield, farmers used pesticides liberally. Owing to the formidable gap between their intake and effect, it took scientists more than half a century to realise that these chemicals were being far from benign in their effects.

Silent wings
• Today, scientific literature is full of instances of the adverse effects of pesticides on birds. Take ddt , once the most popular pesticide, for instance. Its most use occurred in California where, between 1949 and 1957, it was applied just thrice in Clear Lake to control gnats. It not only eliminated its intended targets, but brought the population of Western Grebes ( Aeschmorphorus occidentalis ) from a thousand breeding pairs to zero as well. It then went on to suppress the bird population for years to come.

l There are many such instances of organochlorines and endocrine disrupters affecting birds. In the 1980s, experts discovered that since 1950, sex ratios in certain population of North American gulls and the Caspian Tern (Sterna caspia ) became skewed, favouring females. Homosexual pairings accounted for less than 10 per cent of the breeding pairs on Santa Barbara Island, California, between 1972 and 1980.

These pairs were associated with abnormally large number of eggs laid. After much research, scientists found the unbalanced sex ratio to be the result of feminisation of male embryos through exposure to ddt and its metabolics. The most disproportional sex ratios and the highest incidence of homosexual pairing in Western Gulls occurred in a local ddt 'hot spot' in Los Angeles, California.

l In the mid 1980s Black-billed magpies (Pica pica ) suddenly suffered local population declines for no apparent reason in many parts of the us . However, extensive research revealed the true story: the birds were suffering from contamination by a organophosphate pesticide called femphur. The pesticide was usually used to control warbles or fly larvae in cattle. Poured on backs of cattle, it kills the larvae in the cattle's bloodstream. It was an effective way to eliminate the insects. The only problem was that it remained active long after its application.

The magpies were its first or primary victims. It claimed Red-tailed Hawks ( Buteo jamaicensis ) that fed on the magpies as its secondary victims. Soon, reports of many such primary and secondary bird deaths poured in from all parts of the country. Research soon proved that as a pour-on, femphur would pose severe risks to the birds and it was described as a chemical with "extreme toxicity" ( Ecological Applications , Vol 7, No 4).

l In migratory birds, organophosphates can interfere with their ability to orient themselves in the proper direction for migration. When consumed, these chemicals are stored along with the birds' fat reserves. During the long migratory flights, the fat reserves are used up and the chemicals are 'liberated', disorienting the birds.

l The Californian condor, once common in California and its suburbs, lost a formidable percentage of their population, and by 1982, there were just 20 left. Now, none exist in the wild and only 50-60 in captivity. Accumulation of pesticide content in body tissues, lead poisoning through gun-shot carcasses and poisoning through baited rodent pests have been forwarded as some of the primary causes of this drastic decline.

l The us 's national bird and a long-standing symbol of power and elegance, the bald eagle, now classified endangered, continues to fall prey to endocrine disrupting chemicals through their food sources such as contaminated fish. As in all their victims, these chemicals led to premature cracking of the bald eagle egg shells.

l The uk , like its transatlantic neighbour, suffers from similar afflictions. The uk 's indigenous grey partridge is a bird of arable landscape. Nick Sotherton, research manager for the Farmland Ecology Unit of the uk -based Game Conservancy Trust, writing in Pesticide News , says that in the last 40 years, these birds have suffered drastic population losses. These chicks feed on insects. Pests, contaminated by pesticides and herbicides, are believed to be the main factor in chick losses.

l Reports of bird deaths due to pesticide intake pour in from all corners of the world. In another such instance, the uk reported a drop in the last 20 years of more than 75 per cent in song thrush population, found mainly on its lush farmlands. The culprits -- an easy guess -- are pesticides used against slugs and snails -- food thrushes depend on.

l In Vienna, a massive bird mortality accident occurred in Tuleca County from late December 1991 to early January 1992. Thousands of birds died, and an autopsy of 943 bodies revealed carbofuran, a maize seed dressing, as the cause of death.

l South Africa ( sa ), too, has reported several pesticide-related bird deaths. "Cranes and other bird species are being affected by extensive use of these chemicals," reported the sa newsdaily Antidote in 1993. "Farm workers in Overberg, South-Western Cape, scatter grain soaked in pesticide to kill guinea fowl.

This has proved to be a major factor behind numerous blue crane ( Anthropoides paradiseus ) deaths," it reported. The paper listed the organochlorine dieldrin as one of the major killers.

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Indian scenario

More studies are required to confirm the number of vulture/bird death reports in India. However, it has been known that urbanisation and deforestation have been responsible for a gradual decrease in several species of birds of prey. Scientists and ornithologists say that in southern India, where domestic livestock carcasses are rare and cannot be depended upon as primary food source, vultures have suffered population losses. But they are yet to explain their decline in North India.

Sprayed to death
"Global comparison of organochlorine concentrations indicated that resident birds in India had the highest residues of hch s and moderate to high residues of ddt s," reads a recent report from the department of environment conservation at Ehime University, Japan.It adds that migratory birds which spend their winters here may also have formidable amounts of these chemicals. Experts speak of numerous instances of pesticide poisoning in Indian birds.

Cranes, says George Archibald of the International Crane Foundation ( icf ) have been affected by the pesticide menace: "Pesticides like ddt are the major culprits. These have fatal effects on the cranes ( sarus ) which adorn the agricultural fields of north India." The sarus , quite adaptable, lives close to human habitation and depends on food grain as its primary food source. This is why they are found in the agricultural land of north India. But its feeding grounds have become their killing fields. The cranes eat grains treated with pesticides which proves fatal. This either kills them or affects their calcium metabolism by making the shells of their eggs thin. This eventually hampers the propagation of the species, Archibald explains.

V S Vijayan, director of the Coimbatore-based Salim Ali Institute of Natural History and Ornithology, confirms the sarus deaths. The farming community around Bharatpur uses aldrin, a banned organochlorine, to protect their mustard crop. Later, mustard oil cakes contaminated with the chemical are used as cattle feed. The sarus gets the pesticide somewhere along the food chain. "We had also detected organochlorine residue in eggs and bodies of colonial nesting birds such as grey heron, cattle egret, spoon bill, painted stork and several others," says Vijayan. An itrc study confirms the presence of these chemicals in cattle feed. The study found significant levels of organochlorines, hch and other toxins in commercially--produced cattle feel available in the country.

Deformed and thin egg shells of the lesser fish eagles were found at the Corbett National Park, India, from 1991 to 1996 by Bombay-based ornithologist Rishad Naroji. Eggs from seven nests monitored during this period did not hatch, many young birds were found dead in the nest. "The species is seriously threatened at Corbett and is likely to be similarly affected throughout its range in India," says Naroji. He voices his suspicions, "One reasonable guess would be that the birds have been affected by pesticides. Significant levels of dieldrin were found in the egg shells based on a quantitative analysis." Further, the waters of river Ramganga, the park's lifeline, have high levels of this pesticide, he says.

A 1997 paper by Naroji in the Journal of the Bombay Natural History Society says the higher reaches through which Ramganga flows are covered with terraced cultivation where farmers used pesticides on a large scale. "The contaminants probably run off into the water system during the heavy monsoon which the region experiences.

This is a matter of great concern as even other animal species in the river could be getting affected," he says, "But we do not know, due to lack of research and information in this area."

While information about decline in vulture population from most parts of India is sketchy, Naroji says there is definitely a decline in southern India. This could be due to efficient disposal of carcasses and cleaner eating habits, he says. As far as North India is concerned, he says: "They have definitely suffered losses in some areas." He cites the Bharatpur phenomenon and says the decline is very likely due to pesticides. "All around the world and in India too, aldrin and dieldrin has been banned. But in Bharatpur, farmers still depend heavily on aldrin," says Naroji. He questions whether these pesticides are past surplus or if they are still being manufactured in India.

Bharatpur is in Rahmani's mind too. Perturbed by the population crash, he thinks that apart from pesticides, there could also be the chance of an unknown avian disease. "But this," he says, "has to be proved by a proper study." And the lack of studies on avian deaths remains the single biggest hurdle in assessing the effects of pesticides. Extensive research is indispensable, agree experts, if we are to save not only the birds, but ourselves too from this chemical bane.

According to Rahmani, vultures and cranes are not the only birds being affected. Rahmani cites the instance of the ring-tailed fishing eagle which disappeared from Bharatpur as a breeding species. "There is no proper study on the effect of pesticides on birds and wildlife so we think the problem does not exist in India. Only through studies will we know the magnitude of this problem. At present, ignorance is bliss," he laments.

Among Indian states, West Bengal has witnessed a recent decline in birds of prey such as eagles, harriers and vultures, informs Kushal Mukherjee, founder-member of the Calcutta-based environmentalist group, Prakriti Sansad . A journal by the Sansad notes: "One big reason for the death of predatory birds is the use of pesticides. Poisonous chemicals like ddt enter their bodies when they feed on smaller animals and reptiles like frogs and snakes. These smaller animals eat insects whose bodies contain these insecticides."

A study on the effect of pesticides on birds was done by S K Maitra and his team from the Reproductive Endocrine Physiology Laboratory of the Burdwan University, West Bengal, during 1987-91. The study concentrated on grain--eating birds like parakeet, munia and weaver bird in the state. Maitra notes long-term effects of organophosphate insecticides: "It does not cause mortality at low doses but causes damage to reproductive system."

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Losing the poets

When noted British author Aldous Huxley finished reading Silent Spring , he was distraught. "We are losing half the subject matter of poetry," he remarked. He was not quite right. The chemicals have found their way up the food chain and after the birds, humans could be next. Huxley might well have added that not only is the subject matter of poetry being lost but there is a good chance of losing the poets as well. The pesticide threat is very real, and any delay in tackling it could prove to be a very expensive mistake.

The us, one of the first countries to suffer pesticide-related avian deaths, was also one of the pioneers in spearheading a legal fight against pesticides. The first signs that the chemicals were not being entirely benign in their effects came soon after the us Green Revolution. Research indicated that despite all the hype, high-input agriculture, based on the application of these chemicals, was in no way an improvement over traditional low-input agriculture. Silent Spring's poetic language and the touching tales of bird deaths and environmental degradation led to the birth of environmental activism in the country. Since then, public and government awareness has increased, and the us has taken several steps in curbing the use of pesticides.

The us Federal Insecticide, Fungicide and Rodenticide Act ( fifra ) is a sign of hope. fifra ensures that all pesticides carry extensive instructions as well as cautionary advises to prevent deaths of unintended targets. But apart from this act , the us has taken several other steps to curb decline in avian population. The country has adopted legal measures to prevent habitat destruction and use of potentially harmful pesticides. Methods suggested by conservationists include raising public awareness about the beneficial activities of birds and the need to protect them. Ecological studies, a must before other steps can be adopted, are not so rare in the us . Consequently, the country is well prepared to fight the threats to avian population.

India's own silent springs
Acts like fifra seem to be a distant dream in India and other Asian countries where the basic prerequisites -- extensive studies -- are conspicuous by their absence. Right now, India lacks information required to take any step to curb pesticide poisoning not only in birds and animals but in humans as well. Studies like the one conducted by the icmr are extremely rare. More studies, agrees Rahmani and other experts, should be encouraged. Though time-consuming, only these can pave a way for legal action, bans and our own equivalent of the us 's fifra .

As far as government policies to curb the pesticide menace are concerned, India, continues to turn a blind eye. Banned pesticides, as Archiebald and Vijayan point out, are often used with impunity and ignorance by the farming community, resulting in frequent bird deaths. Lack of research and public interest limits the number of such reports and subsequent investigations. The government, say environmentalists, should recognise the toxic pesticides and not only ban them but launch campaigns to illuminate the farmers of the dangers of pesticides. Pesticides should not be included in health programmes, as they have been in the past. Further, the government should meticulously regulate the pesticide industries.

By 1996, India's pesticide industry had an installed capacity of 1,16,000 tonnes per annum of which about 70,000 tonnes was in the organised sector. The rest, comprising 500-odd units, belong to the small-scale sector. It is doubtful if the government actually has any appreciable control over these smaller manufacturers. With liberalisation, restrictions on pesticide manufacturers were lifted, and now, no license is required to manufacture most toxic pesticides except aluminium phosphide, dimethoste, quinalphos, carbyl, phorate and fenitrothion. And though government data show a decline in pesticide consumption, production has risen significantly (see graph: Growing menace ).

By 2000, says a Planning Commission study, India's pesticide consumption would be some 1,18,000 tonnes. What the study leaves out is the fact that if pesticides are used indiscriminately, numerous bird and animal species stand a good chance of being wiped out forever. "Ignorance is bliss for the politician and the bureaucrat. Apart from the influence of industrial lobbies which may operate underhand, India's overt governance systems themselves are incompetent," says a leading environmentalist. This manifests itself best in the fact that there are very few studies on pesticides and their impacts on humans and wildlife.

But in India, pesticides may not be the only threats to vultures. Recent newspaper reports have revealed how quacks in northern parts of the country were using vulture remains as 'medicines'. Villagers were being offered up to Rs 3,000 -- a significant amount by Indian standards -- for vulture bodies. This led to massive vulture-hunting sprees and consequential, the birds suffered tragic population declines in these regions. Not only the government needs to be educated about the importance and value of preserving these birds but the people as well. Non-governmental organisations should take up these issues at grassroots level, telling villagers and farmers why we need to protect the birds. Environmental education, almost non-existent in schools in the rural parts of the country, could also go a long way towards developing a nation of well-informed, environmentally conscious citizens. There is no quick way out of this mess. Studies, well-planned policies and firm control and regular monitoring of the pesticide industry seem to be the only answers in sight. The canary once saved the lives of thousands of farmers. We should do the same for these winged friends, if not in gratitude then at least because they are truly wonderful creatures. But till the government and the people do not wake up, every can of pesticide sprayed on the fields will take India a step closer to its own silent spring.

Based on a note provided by Asad R Rahmani, director, Bombay Natural History Society, and inputs provided by Padma S Vankar of IIT, Kanpur; Karim Ahmed of World Resources Institute, Washington, DC; Ranjita Biswas, Calcutta; and Kazimuddin Ahmed, Priti Kumar, Amit Nair, Manish Tiwari and N Venugopalan of CSE. Copy written by Arnab Ray Ghatak