The Indian vulture crisis: a drug, a food chain and a slow recovery

The Indian vulture (Gyps indicus), also called the long-billed vulture, was among several South Asian vultures hit by a rapid population collapse. The crisis was not confined to this one species: white-rumped and slender-billed vultures were also affected. A central cause was veterinary diclofenac, a pain-relieving drug given to livestock. When vultures fed on treated animals that had died, residues could cause fatal kidney failure.

The mechanism was established through field observations and toxicology studies, turning an apparent mystery into a preventable exposure pathway. But banning a drug did not instantly restore populations. Vultures breed slowly, toxic substances can remain available through misuse or other veterinary drugs, and fragmented nesting colonies are difficult to monitor. The latest India-wide assessment provides a more specific picture of where the Indian vulture still breeds.

How a livestock drug reached a scavenger

Diclofenac was widely used to treat cattle and other livestock. A vulture could be exposed by eating tissue from a carcass containing even a small residue. In susceptible birds, the drug disrupts kidney function; visceral gout and kidney failure follow. Because vultures consume carrion and may feed quickly, a contaminated carcass can expose several birds.

Scientists linked diclofenac to the collapse by combining evidence: carcasses and dead vultures were examined, toxicology tests were conducted, and controlled studies demonstrated lethal effects at residues found in treated livestock. The connection was more specific than a general association between farming and declining birds. It identified a pathway that could be addressed by restricting veterinary use and promoting drugs shown to be safer for vultures.

The scale of decline varied by species and region. It is inaccurate to compress the crisis into one exact percentage for “Indian vultures” as a whole. The 2025 Wildlife Institute of India report describes severe historical losses and continuing concern, while also documenting current nesting sites species by species.

What the latest nest assessment found

India’s 2023–2025 assessment was the first systematic country-wide effort to focus on resident breeding vultures. For the Indian vulture, field teams recorded 1,379 nests across 110 sites in 10 states; 1,029 nests were classed as active. Using the assessment’s method, the report estimated at least 2,058 to 2,758 breeding adults. Madhya Pradesh and Rajasthan held a large share of the recorded sites, with Madhya Pradesh alone accounting for 715 nests.

These numbers describe the survey’s evidence and its coverage. They are not an all-age total, and the report notes that population assessment remains challenging because nesting sites are scattered and some areas are difficult to survey. A nest count can reveal active breeding locations, but it does not tell us how many birds are outside the sampled sites or how survival will change next year.

The assessment also distinguishes the Indian vulture from other species in the crisis. White-rumped vultures, slender-billed vultures and red-headed vultures have different distributions and nesting records. Conservation plans need those distinctions because a stronghold for one species may not protect another.

A ban is one step, not a food-safety system

India prohibited veterinary diclofenac in 2006, and Nepal and Pakistan also restricted its veterinary use. Regulations reduced a major source of exposure, but implementation matters: human-use formulations can be misused on livestock, and other non-steroidal anti-inflammatory drugs may also be dangerous. Conservation groups test veterinary medicines and promote alternatives with evidence of safety, including meloxicam and tolfenamic acid.

Vulture-safe zones try to protect a landscape around nesting colonies by checking drug availability, carcass contamination and community practices. Captive-breeding centres provide an additional safety net for the most threatened species, while field surveys track whether wild colonies persist. The Indian assessment’s 2023–2025 nest data are useful in this context because they identify locations where protection and monitoring can be focused.

Vultures also provide an ecological service by removing carcasses. Their decline can change how dead livestock are disposed of and can affect other scavengers. The Tasmanian devil is another native scavenger whose conservation is monitored for a different threat, showing why food-web roles matter even when the cause of decline differs.

Reading recovery without declaring victory

Some studies found that the steepest decline slowed after veterinary diclofenac restrictions, but stabilisation is not the same as recovery. The 2025 national assessment still describes the focal vulture species as highly vulnerable and identifies the need for continued monitoring. A growing number of active nests at surveyed locations would be encouraging; a single nest total cannot show that the entire historical population has returned.

The central lesson is unusually concrete: a routine veterinary treatment can move through a carcass into a scavenger and produce a population-level crisis. The response must follow the same chain in reverse. Medicines need to be safe, carcasses need to be monitored, breeding sites need protection, and counts need to be repeated with comparable methods. Only then can conservation teams tell whether the intervention is translating into durable recovery.