New paper reveals diet composition and the continued risk of toxic drug contamination for Gyps vultures in India.

DNA techniques used on faecal material collected from vultures across India reveal that domestic ungulates still predominate as the main food source of White-rumped and Long-billed Vultures, even for those using protected areas. The findings are of great importance for vulture conservation in India because they show that vultures would still be exposed to any toxic veterinary non-steroidal anti-inflammatory drugs (NSAIDs) that remain in use or might be introduced in the future. Veterinary use of the pain-killing drug diclofenac caused the drastic declines in vulture populations during the last 30 years and diclofenac and other toxic NSAIDs are still being used.

The research, published in the journal Biological Conservation, was led by Mousumi Ghosh-Harihar and Uma Ramakrishnan of National Centre for Biological Sciences (NCBS) in Bangalore. The work was funded by a joint Cambridge University – NCBS fellowship intended to encourage collaborations between the UK university and NCBS, and additional funds from the Raptor Research and Conservation Foundation. The work involved a network of collaborators who collected over 600 faecal samples from North, Central and South India of which over 400 could be fully analysed to identify both the species of vulture the sample came from, its sex and the types of food it had eaten.  It reveals that despite changing cattle carcass disposal practices and the fact that wild prey such as deer can also be an important food source, a high proportion of samples contained DNA from domestic livestock (cows and water buffalo). This was the case even for samples collected in and near protected areas. The one exception to this was samples from South India where much higher proportion of samples (77%) contained only wild species, but even there, domestic ungulates were still an important component.

The paper  reveals the wide range of food items consumed (28 species), including cattle, water buffalo, goat, sheep, spotted deer, sambar, pig, chinkara, gaur, nilgai, elephant, tiger, common leopard, rhesus macaques, wild dog, jackal among others and has important conservation implications.

Prof. Uma Ramakrishnan, senior author explained “Our results emphasise the need for effective bans of diclofenac and other toxic NSAIDs such as nimesulide as these drugs are still widely used in cattle across the country. We hope the implications of this work will contribute to on-ground actions for vulture conservation and recovery.”

Mousumi Ghosh-Harihar who led the work said “Collecting and processing data for large scale analyses is always challenging, more so from non-invasively collected samples. Such samples often yield poor quality DNA. Diet metabarcoding helped us overcome these challenges and allowed us to generate data on vulture diet from large number of faecal samples very efficiently and reliably. The pipeline (designed by us) allowed us to simultaneously identify the vulture species, its sex and dietary species”

Co-author Vibhu Prakash, vulture expert and retired BNHS scientist said “We were pleased that the captive vultures at Pinjore could be used to help calibrate the food composition in a controlled environment – another benefit of having populations of these critically endangered species in captivity.”  He added “This study was important to furthering our understanding of what happens in the wild and would have been difficult using any other method.”

Co-author Rhys Green, of Cambridge University, former Chair of SAVE, said “Using these latest DNA techniques to establish what vultures were feeding on in the wild is important and something that is otherwise extremely difficult to get objective information on. Some cattle carcasses are skinned before vultures feed on them, so identifying foods with a microscope to classify hair from regurgitated pellets or faeces can be misleading. It took great care and effort not only to obtain the samples, but also to develop the techniques to identify the foods and, importantly to establish that every faecal sample used in the calculations came from a vulture. It’s a great credit to those who worked hard in both the field and the laboratory. The results shows that most vultures would still be exposed to any toxic veterinary NSAIDs in use, even if they were based in the heart of a large National Park.”

Full Reference for the paper:

Ghosh-Harihar, M., Yadav, N., Gurung, N., Darshan C.S., Shashikumar, B., Vishnudas C., Prakash, V., Green R.E., & Ramakrishnan, U. (2024) Spatial patterns in the diet of Gyps vultures in India and their implications for conservation. Biological Conservation 292, 110551.

Full paper available on request from the authors or from chris.bowden@rspb.org.uk

Compiled by Chris Bowden

 

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