May 12

The ban on a drug blamed for catastrophic declines in Asian vulture populations is showing the first signs of success, according to new research.

Photo of Asian white-backed vulture on ground

The Asian white-backed vulture has been virtually wiped out by poisoning from diclofenac.

Vultures in decline

Vulture populations in South Asia have undergone a severe crash in recent years, with populations of the Asian white-backed vulture all but disappearing, and the slender-billed vulture and Indian vulture also being brought to the brink of extinction. All three species are classified as Critically Endangered by the IUCN.

Photo of slender-billed vulture

The slender-billed vulture, another Asian vulture species under threat.

The main culprit in the decline has been identified as the veterinary drug diclofenac, used to treat pain and swelling in livestock. This drug is toxic to vultures, which are poisoned after feeding on contaminated livestock carcasses.

Diclofenac now banned

In a move to protect vultures, the governments of India, Nepal and Pakistan banned the use of diclofenac for livestock in 2006. This new study, published in the journal PLoS One, set out to assess how effective the ban has been in protecting vulture populations.

By measuring the concentration of diclofenac in livestock carcasses before and after the ban, the research revealed that the proportion of contaminated cattle carcasses in India dropped by about 40% between 2006 and 2008. In those carcasses that were still contaminated, the concentration of the drug was also significantly lower after the ban.

Photo of Indian vulture landing at kill site

An Indian vulture landing at a kill. Vultures can travel long distances to reach food, exposing large portions of the population to contaminated carcasses.

Vultures still in trouble

In light of these changes, the rate of vulture declines is expected to slow. However, the populations of all three species are still decreasing, and are unlikely to recover unless the use of diclofenac is eliminated.

Diclofenac manufactured for human use is still being used illegally in India to treat cattle, and other drugs known to be toxic to vultures, or with unknown effects, are still legally used by vets. An alternative legal drug, meloxicam, is safe for vultures and is being increasingly used, although it has not yet replaced diclofenac.

Photo of Asian white-backed vulture in flight

Asian white-backed vulture in flight.

According to one of the authors of the study, Dr Richard Cuthbert of the RSPB, “This shows how much progress has been made, but there is still a job to do to make sure that safe alternative drugs are used. Unfortunately some of the alternatives have not been tested for their safety to vultures and one drug in increasing use, ketoprofen, is already known to be toxic to vultures.”

Long road to recovery

Although the results of the ban on diclofenac are good news for Asia’s vultures, it may be too soon to say whether vulture populations will recover.

Dr Munir Virani of the Peregrine Fund, which helped support research into the cause of South Asia’s vulture decline, said that the initial results were encouraging, but that, “we must be extremely cautious about jumping the gun to say that vulture populations are on the road to recovery.”

Read the BBC story – Drug ban helps vulture recovery.

Find out more about the Peregrine Fund’s Asian Vulture Crisis project.

View photos and videos of vultures on ARKive.

Liz Shaw, ARKive Species Text Author