Ipsa Tripathy
Bhubaneswar: Vultures are often associated with death because they feed on the remains of dead animals. Ecologically, however, they perform an important function: they are highly specialised scavengers that rapidly remove animal carcasses from the environment. This makes them an important part of nutrient cycling and the functioning of terrestrial ecosystems.
Their importance became particularly clear in India during the dramatic decline of several vulture species in the 1990s and 2000s. The decline demonstrated that removing a scavenger from an ecosystem can have consequences far beyond the species itself.
Nature’s Scavengers
Vultures are adapted specifically to locate and consume carrion. Species belonging to the genus Gyps, including the white-rumped vulture (Gyps bengalensis), Indian vulture (Gyps indicus) and slender-billed vulture (Gyps tenuirostris), depend heavily on carcasses of large mammals.
Their ability to consume carrion efficiently is partly related to their specialised anatomy and physiology. Vultures have strong digestive systems capable of processing decomposing animal tissue, including material containing large numbers of microorganisms. By removing carcasses relatively quickly, vultures help transfer nutrients from dead animals back into ecological cycles.
Why Rapid Carcass Removal Matters
A dead animal is a source of food for many organisms, but decomposition can also provide opportunities for pathogens and other scavengers. Vultures are particularly effective because they can consume large quantities of carrion rapidly. Their feeding therefore changes how long carcasses remain available to other organisms.
This ecological service became particularly important in India after vulture populations collapsed. Research has linked the decline of vultures with increases in feral dog populations around livestock carcass resources and identified potential consequences for human health, including increased rabies risk. These studies estimate that the loss of vulture-mediated carcass disposal had substantial health and economic consequences, although the precise magnitude of these effects remains dependent on local conditions and assumptions in the models. The important scientific point is that a change in one part of a food web can alter the abundance and behaviour of other species.
The Diclofenac Disaster
India’s vulture crisis is one of the clearest examples of how a chemical introduced for one purpose can produce an unexpected ecological effect. During the 1990s, the veterinary use of the non-steroidal anti-inflammatory drug diclofenac became widespread. Livestock treated with the drug could retain residues in their tissues. When vultures fed on the carcasses of recently treated animals, they could ingest toxic quantities of diclofenac.
The drug causes kidney failure and visceral gout in vultures, leading to death. Research identified veterinary diclofenac as the principal cause of the catastrophic decline in three Gyps species across South Asia. The scale of the decline was extraordinary. Surveys found that by 2007, the Indian population of the white-rumped vulture had fallen to approximately 0.1% of its abundance in the early 1990s, while Indian and slender-billed vultures had also undergone severe reductions.
India, Nepal and Pakistan introduced measures in 2006 to prevent veterinary use of diclofenac. The ban reduced contamination of livestock carcasses, although the drug did not immediately disappear from the environment. Studies subsequently found that the decline in Gyps populations slowed after the ban, consistent with the reduction in diclofenac exposure. However, elimination of the drug from the vultures’ food supply has remained incomplete, and other veterinary drugs have also become a concern. This illustrates an important principle in wildlife conservation: protecting a species sometimes requires managing the environment in which it feeds, not simply protecting its nesting sites.
Protected Areas Do Not Completely Remove the Risk
Protected forests and wildlife sanctuaries can provide important habitat, but vultures are highly mobile birds and may travel considerable distances while searching for food. Research using DNA metabarcoding of vulture droppings has found evidence of domestic cattle and water buffalo in the diets of vultures both inside and outside protected areas. The study analysed 642 dropping samples collected between 2018 and 2022 from sites in several Indian states. This finding is important because livestock carcasses can remain a potential source of veterinary-drug exposure even when vultures are foraging around protected areas. Conservation therefore has to extend beyond the boundaries of reserves.
Vultures are also part of the broader process through which nutrients move through ecosystems. Animal tissue contains carbon, nitrogen, phosphorus and other elements. When an animal dies, these materials enter decomposition processes. Scavengers accelerate the transfer of this organic material through food webs. Vultures themselves become prey or sources of nutrients after death, while their waste contributes organic material to the environment. Their ecological role therefore connects animal populations, microorganisms, soil processes and nutrient cycling.
Why Vulture Conservation Matters
The vulture decline demonstrates that biodiversity is not simply about maintaining a list of species. Species perform ecological functions, and the loss of a functionally important species can change the behaviour of other organisms and alter ecosystem processes. For vultures, conservation requires several measures: preventing exposure to toxic veterinary drugs, maintaining safe food sources, protecting breeding populations and monitoring the use of pharmaceuticals that may affect scavenging birds.
The development and use of vulture-safe veterinary medicines, including alternatives such as meloxicam, has been an important part of conservation efforts. At the same time, research continues to identify other drugs that may pose risks to vultures. Vultures therefore matter for a reason that extends beyond their appearance or their role as scavengers.
They are part of an ecological system that processes dead biomass, transfers nutrients and influences interactions among scavengers, microorganisms and other animals. Their decline in India provided a striking demonstration of what can happen when one specialised component of an ecosystem is removed. Vultures do not prevent death. They help nature process what comes after it.