Research paper highlights trends in vulture population

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Long-billed Vulture - BNHS Photo library

Surveys by BNHS and RSPB reveal positive as well as negative effects on vulture populations

The vultures, known for their valuable ecosystem services of disposing of cattle carcasses, have recently been addressed as 'sanitary workers' rather than scavenging birds by the Madras High Court. A research paper recently published in the journal 'Bird Conservation International', notes that the population of Oriental White-backed Vulture appears to have stabilized but that of the Long-billed vultures is still declining.

Research Paper:

The research paper "Recent changes in populations of Critically Endangered Gyps vultures in India" written by multiple authors with Dr. Vibhu Prakash (Deputy Director and Head of the BNHS-Vulture Conservation Breeding Programme) as the lead author, is based on the nation-wide surveys carried out on pre-determined routes in different parts of the country during 2015 by BNHS supported by RSPB, U.K.

The estimates from this survey have been incorporated into the global estimates for the three species calculated by BirdLife International and CMS Vulture Multi-species Action Plan.

Dr. Toby Galligan, Conservation Scientist, RSPB, U.K. co-author of the paper, informed that the new population trends and size estimates for these species in India are published in this paper. Results from the survey conducted in 2015 were added to those from six previous ones to recalculate population trends. A more robust method was used in 2015 than in 2007 to recalculate the population size.

Dr. Rhys Green, Conservation Scientist from RSPB, U.K, a co-author, said that the new best estimate of population size for all three species is much lower than previously estimated. It is important to note that the difference in population size estimates between 2007 and 2012 analyses is mostly because of a better method that allows for the position of many transects near protected areas, where vultures are more plentiful, and not because vulture numbers have changed greatly between the two years.

Dr. Prakash said that diclofenac is only one of over a dozen drugs known as non-steroidal anti-inflammatory drugs (NSAIDs) available in India. The toxicity experiments showed only one NSAIDs called meloxicam is non-toxic to vultures.

However, it is also known that four other NSAIDs (aceclofenac, carprofen, flunixin, ketoprofen) are toxic to vultures, none of which are banned, and another drug, nimesulide, is probably toxic too. The evidence for either way for the remaining five or so available NSAIDs is lacking but could be considered potentially vulture-toxic until shown to be otherwise.

The three resident species of Gyps vulture, formerly numbering tens of millions in total, are now considered critically endangered. The use of other vulture-toxic NSAIDs in cattle could prevent the recovery of Oriental white-backed vultures and continue the decline of long-billed and slender-billed vultures. Dr. Deepak Apte, Director, BNHS says, "the paper is reminder of the vulture crisis in India which is far from over and more regulatory actions on vulture-toxic NSAIDs are required to save vultures from extinction."

Surveys:

The population of resident Gyps vultures, Oriental white-backed vultures (Gyps bengalensis), long-billed vultures (Gyps indicus) and slender-bill vultures (Gyps tenuirostris) in India suffered catastrophic decline in the 1990s and 2000s. BNHS has been monitoring the population of these vultures across India since early nineties.

The veterinary drug diclofenac, which is a wonder drug for pain relief in cattle, was found to be extremely toxic to vultures and was implicated in the population crash of these species. Every four years surveys to count vultures are repeated covering approximately 15,500 km roads among 154 road transects and 13 states in northern, central, western and north-eastern India.

In 2007, crude estimates of the population size for each species were 11,000 for Oriental white-backed Vultures, 45,000 for long-billed vultures and 1,000 for slender-bill vultures. In 2012, the survey findings were encouraging reporting a slowdown in the decline for all three species and the possible first sign of recovery in the Oriental white-backed vulture.

In 2015, estimates were approximately 6,000 Oriental white-backed vultures, 12,000 long-billed vultures and 1,000 slender-billed vultures which are alarmingly low. "The good news is that the positive trend for Oriental white-backed vulture population appears to be continuing. The bad news is that the long-billed vulture population continues to decline. For the rarest of the three species, the slender-billed vulture, numbers counted are now too small to estimate a reliable trend," notes Dr. Prakash.

The Background:

BNHS has spearheaded the vulture conservation efforts in the country and was instrumental in raising an alarm along with documenting the decline in vulture population since mid 1990s. The Society played an important role in finding the cause of vulture mortality by systematically collecting field evidences and establishing that diclofenac was the sole cause of this decline. The Society's nation-wide surveys carried out every four years established a 99% decline of vulture population in the country by 2007.

BNHS with the help of national and international conservation organisations prepared the Vulture Recovery Plan in 2004 which was incorporated in the Vulture Action Plan of 2006 of Government of India. BNHS was successful in getting the veterinary use of the drug diclofenac banned in 2006. It also helped in finding a safe alternative drug, meloxicam, for vultures and cattle by carrying out safety tests of the drug on vultures in collaboration with IVRI.

BNHS established four Conservation Breeding Centres for vultures in collaboration with state governments, as an insurance against extinction and has been successful in breeding the three above mentioned critically endangered resident Gyps species of vultures in captivity for the first time ever. Efforts are being made to initiate a reintroduction programme by making sure that the habitat in radius of 100 km has low prevalence of vulture toxic drugs along with enough food and habitat for vultures.