Vultures are renowned for their unprepossessing eating habits. But they are also nature’s most proficient macro-scavengers, able to spot a carcass from miles away, then congregate and strip it down to bone in a matter of hours. In this way, vultures provide a valuable service: they minimise the spread of pathogens within the ecosystem. They also provide a sanitary and environmentally inert means of disposal, reducing the need for burial, which can result in environmental contamination through leaching, or for incineration, which consumes fossil fuels and generates emissions.
Sadly, vulture populations worldwide are threatened. The near-extinction of populations of three species of Gyps vultures on the Indian subcontinent provides a dramatic example. There, the birds are being poisoned when they consume livestock carcasses contaminated with residues of diclofenac, a nonsteroidal anti-inflammatory drug, or NSAID. Diclofenac is safe for use by humans and other mammals, but induces visceral gout in some species of vultures. There is evidence that other avian species may be susceptible as well. Exposure to several NSAIDs registered for veterinary use, particularly carprofen, ketoprofen, phenylbutazone, flunixin, ibuprofen and nimesulide, may also be of concern. In the space of a decade the three species of Gyps, once the most common large raptors in the world, have been reduced by 97% - equivalent to the loss of millions of birds.
This unprecedented decline in vulture populations has been exacerbated by the extensive use of cattle and buffalo, and the ready availability of diclofenac to treat their aches and pains. Although diclofenac is gradually being phased out from the Indian markets, residues are still found in the environment, veterinary stockpiles exist and the drug is still allowed for human use. In India, the repercussions on health, economy and culture have been devastating. Wild dogs and rats have now moved in to replace the vultures. Far less efficient scavengers, they leave carcasses only partially consumed. They can also be aggressive, and they are vectors of disease.
Numerous attacks on residents and livestock animals have been reported and India now has one of the worst incidences of rabies in the world (C&I 2007, 24, 11). The Parsi ceremony, which involves placing deceased members on elevated platforms to be consumed and ‘transported’ by vultures, can no longer be performed; too few vultures remain. Instead, the Parsi now have to seek alternative means of disposal, some of which contravene their beliefs.
Before diclofenac was conclusively implicated in the mass mortality, hundreds of dead vultures were collected across the Indian subcontinent. Of these, less than 50 were in sufficiently good condition for residue analyses to be carried out.
In response to this problem, a number of techniques have been developed to detect residues of diclofenac in livestock and vulture carcasses. We are currently developing forensic methodology to detect diclofenac and any other NSAIDs of concern in the hair of livestock animals and the feathers and talons of vultures, via GC-MS. This screening process draws on the same principles used to detect drugs of abuse in human hair and nails.
Hair, feathers and talons were selected for analysis because they are much more resistant to environmental deterioration than tissues and are likely to remain attached to any intact or partial carcass retrieved. Samples of bone and eye tissue from animals dosed with NSAIDs are also actively being sought. The aim is to determine the detectability of NSAIDs in all retrievable carcass matrices and maximise the number of carcasses that can be analysed for residues.
Vulture populations throughout Africa have also declined markedly. However, the change has been more gradual than that observed in India and only recently have African vulture species been up-listed to the IUCN Red Data list. Exposure to the carbamate pesticide carbofuran (Furadan) is currently considered the main cause of vulture mortality in Africa (C&I 2007, 2, 5) A number of NSAIDs are registered for veterinary use throughout the continent and diclofenac was discovered on sale earlier in 2007. There is now concern within the conservation community that presence of diclofenac may pose an additional threat to vulture populations, though this is under debate given that ailing livestock animals are more likely to be slaughtered for human consumption than treated for their aches and pains.
Disseminating the NSAID detection method to collaborators in Africa presents an opportunity for capacity-building, to secure ongoing research interest in vulture monitoring and conservation and to provide additional information for long-term monitoring of vulture populations. Given the known link between exposure to diclofenac and vulture mortality, and the current status of Africa’s vulture populations, it should also be viewed as a preventive measure.
The key was to find the right collaborators and resources. In January 2007, I read about the Foundation for Analytical Science & Technology in Africa (FASTA), a UK-based charity newly formed to develop and provide technological capacity, facilitate research and teaching, and promote understanding of the environment in African universities. In the 12 months since its inception, FASTA has formed the first centre of excellence for analytical science and environmental research in East Africa, based at Jomo Kenyatta University of Agriculture & Technology (JKUAT). FASTA has provided JKUAT with a GC MS, the first at any Kenyan university, and associated environmental monitoring equipment. The centre is now recognised by the Kenyan government as essential to its environmental monitoring initiatives. I contacted Steve Lancaster, managing director of FASTA, explained my research and its intended purpose, and he agreed to a collaboration.
In early 2008 we will set up a pilot project with Anthony Gachanja of JKUAT to implement the NSAID detection methodology at his laboratory. Because NSAIDs mask pain and inflammation, their use is prohibited in many sports, particularly in the horseracing industry. The detection methodology is also being developed with this in mind and one of its applications is to generate revenue for the laboratory so that the analysis of vulture samples is self-sustainable.
The JKUAT will develop a doping assessment service by adapting the method to detect NSAIDs in equine and human hair as well as in the more conventionally analysed urine and plasma. At the same time we will be exchanging information and analytical methodologies with Joseph Lalah, whose student Peter Otieno has received a grant from the Peregrine Fund to investigate the extent of vulture exposure to Furadan. We will also be in close contact with other colleagues actively pursuing vulture/wildlife conservation. Ultimately, the objective is for the JKUAT laboratory to be in a position to receive and screen samples taken regionally from vultures and other wildlife species for a number of compounds of concern.
To achieve its objectives, FASTA is seeking start-up funding to implement the pilot project from 2008 and provide follow-up support into 2010 and beyond if necessary. Any funding obtained will be used for two purposes. The first is to establish a fund to ensure ongoing laboratory costs are adequately met and enable JKUAT to operate at a loss while establishing the NSAID detection method and contract work within the sports industry is being secured. The second is to establish a rolling fund to enable JKUAT to initiate and participate in regional vulture-related research projects and workshops that generate awareness about wildlife conservation and that minimise pesticide/contaminant exposure to wildlife and people.
Once adapted and refined, the NSAID detection methodology will be widely disseminated to other laboratories. It is critical that analytical results be made available as quickly as possible following an event of mass mortality so that measures to alleviate the problem can be implemented. Having to ship samples outside each country would severely delay this process and divert valuable funds that could be better used for the analyses themselves.
Networking and monitoring
Vulture monitoring and conservation efforts are under way throughout Africa. The development of a coordinated monitoring strategy that unites all these efforts is critical. Joining forces with those involved in vulture conservation and monitoring in East Africa represents an important first step. We aim to provide whatever support we can to those involved in monitoring for carbofuran to address this pressing, current conservation issue, whilst developing a means to monitor for diclofenac and other NSAIDs, so that everything will be in place should the need to monitor for them ever arise in the near future.
The Asian vulture crisis has demonstrated that the most common and abundant species have the capacity to become vulnerable in a short period of time. It has taken the better part of a decade to identify diclofenac as the culprit. Meanwhile millions of birds have died.
A species does not have to be rare to be of value, but it only seems to take on importance when its numbers decrease and its absence from our day to day lives and from our environment resonates more loudly. African vulture populations are already struggling in the face of unintentional and deliberate poisoning. They also face dwindling habitat and food resources, for which there is increased competition with people and livestock animals.
In India, surviving vultures are being removed from the wild for captive breeding until the environment is deemed safe for their release. While the captive population now represents the sole hope for the survival of the once abundant Gyps on the Indian subcontinent, there is something tragic and deeply unfair about having to physically remove an animal from its own environment and familiar surroundings because of human activity. Whole generations of children may grow up never experiencing vultures as a regular part of the landscape, as they once were. We cannot let the vultures disappear from our skies, for that is where they belong.