Vulture conservation | leversforhealth

Restore vulture populations to control human rabies

HUMAN INFECTIOUS DISEASE

Rabies (perhaps also anthrax and cholera, but via different mechanisms)

CONSERVATION PROBLEM

Severe vulture population declines and extinction risks for several species

INTERVENTION

In Asia, the intervention is switching from a commonly-used veterinary drug, diclofenac, which causes vulture mortality, to a vulture-friendly veterinary drug, like Meloxicam.

TARGET

Populations of threatened and near threatened vulture species

MECHANISM

Vultures compete with free-ranging dogs for carrion and thus increasing/restoring vulture populations might limit free-ranging dog populations via competition, thereby reducing the risks that humans will be bitten by rabies-infected dogs.

HUMAN INFECTIOUS DISEASE EVIDENCE

OBSERVATIONAL: During vulture declines in India, the free-ranging dog population increased despite a sterilization program, potentially due to reduced carcass competition, but other confounding factors could have been important. MODEL/REVIEW: If it works, the Meloxicam switch and other vulture conservation efforts would be COST-EFFECTIVE, especially because the countries with the most priority areas for vulture conservation also have the highest expenditures related to human rabies (e.g., India, China, and Myanmar).

CONSERVATION EVIDENCE

Due to 95-99% vulture population declines, 5 out of 9 Indian vulture species have recently become endangered. VETMED/MODEL: Diclofenac poisoning alone can explain rapid declines in vulture populations. BEFORE-AFTER: Since the 2006 diclofenac ban, Indian vulture populations have stopped declining, but have not yet begun increasing.

LOCATION AND SPATIAL SCALE

Vulture declines are worst in South Asia and Africa (where rabies risks from free-ranging dogs are highest) and the Iberian Peninsula. Diclofenac may be used less in Africa, so other interventions might be important there. There is a multi-country Asian diclofenac ban.

TEMPORAL SCALE

Vulture declines occurred over a few decades. It took at least one decade to stop the population declines in India, and restoration may take much longer due to low birth rates.

HEALTH SUCCESS METRICS

Hypothetically, decreased free-ranging dog population sizes, number of dog bites reported, and/or rabies cases or deaths, but no such outcomes have been measured yet.

CONSERVATION SUCCESS METRICS

Stabilized vulture population sizes and reduced number/percent of carcasses containing diclofenac

HUMAN CO-BENEFITS

Aesthetics and economic benefits associated with rapidly-removed carrion and spiritual and cultural values associated with vultures (e.g., Parsi religion)

CONSERVATION CO-BENEFITS

Restored food web functioning, reduction in contacts at carcasses that are quickly removed and thus maybe less disease transmission among mammalian scavengers

COLLATERAL HUMAN IMPACTS

Minor vulture–human conflicts may occur (e.g., smell, nuisance).

COLLATERAL CONSERVATION IMPACTS

None known

SOCIAL ACCEPTABILITY

Generally socially acceptable (e.g., 94% of Namibian farmers think vultures are useful), but some vulture-human conflicts exist (e.g., farmers think vultures hurt livestock, poachers kill vultures to avoid detection, etc.).

EQUITY CONSIDERATIONS

Meloxicam is not as cheap as diclofenac (though it is more effective at lower dose), so the ban might be felt disproportionately by the poorest people. Governments imposing these bans could run assistance programs to fix this issue, if it exists.

PRACTICALITY/CHALLENGES

If large free-ranging dog populations can outcompete vultures at carrion, additional measures will be needed to restore vulture populations, and it is therefore unclear if vulture restoration alone can reduce free-ranging dog populations. Other threats to vultures still exist (e.g., poison baits, which are toxic to vultures, are used for mammalian predators, especially in Africa.)

STATUS

Diclofenac is banned in India and surrounding countries, and there is a solid cost-benefit analysis for the ban. But vulture poisoning is ongoing elsewhere; for instance, diclofenac is used in Spain.

RESEARCH NEEDS

Critical need for data regarding free-ranging dog populations, human bite cases, and human rabies incidence to evaluate the human health impacts of the ongoing diclofenac ban.

REFERENCES

BEFORE-AFTER STUDIES

A. Markandya, T. Taylor, A. Longo, M. N. Murty, S. Murty, K. Dhavala, Counting the cost of vulture decline—An appraisal of the human health and other benefits of vultures in India. Ecological Economics. 67, 194–204 (2008).

V. Prakash, M. C. Bishwakarma, A. Chaudhary, R. Cuthbert, R. Dave, M. Kulkarni, S. Kumar, K. Paudel, S. Ranade, R. Shringarpure, R. E. Green, The Population Decline of Gyps Vultures in India and Nepal Has Slowed since Veterinary Use of Diclofenac was Banned. PLoS One. 7 (2012), doi:10.1371/journal.pone.0049118.

MODELING STUDIES

R. E. Green, I. Newton, S. Shultz, A. A. Cunningham, M. Gilbert, D. J. Pain, V. Prakash, Diclofenac poisoning as a cause of vulture population declines across the Indian subcontinent. Journal of Applied Ecology. 41, 793–800 (2004).

REVIEWS

A. Santangeli, M. Girardello, E. Buechley, A. Botha, E. D. Minin, A. Moilanen, Priority areas for conservation of Old World vultures. Conservation Biology. 33, 1056–1065 (2019).

OTHER SUPPORTING INFORMATION

A. Balmford, Pollution, Politics, and Vultures. Science. 339, 653–654 (2013).

E. R. Buechley, Ç. H. Şekercioğlu, The avian scavenger crisis: Looming extinctions, trophic cascades, and loss of critical ecosystem functions. Biological Conservation. 198, 220–228 (2016).

L. Gangoso, R. Agudo, J. D. Anadón, M. de la Riva, A. S. Suleyman, R. Porter, J. A. Donázar, Reinventing mutualism between humans and wild fauna: insights from vultures as ecosystem services providers. Conservation Letters. 6, 172–179 (2013).

R. E. Green, J. A. Donázar, J. A. Sánchez‐Zapata, A. Margalida, Potential threat to Eurasian griffon vultures in Spain from veterinary use of the drug diclofenac. Journal of Applied Ecology. 53, 993–1003 (2016).

J. C. Morante-Filho, D. Faria, An Appraisal of Bird-Mediated Ecological Functions in a Changing World. trcs. 10 (2020), doi:10.1177/1940082917703339.

D. L. Ogada, M. E. Torchin, M. F. Kinnaird, V. O. Ezenwa, Effects of vulture declines on facultative scavengers and potential implications for mammalian disease transmission. Conserv. Biol. 26, 453–460 (2012).

D. Ogada, P. Shaw, R. L. Beyers, R. Buij, C. Murn, J. M. Thiollay, C. M. Beale, R. M. Holdo, D. Pomeroy, N. Baker, S. C. Krüger, A. Botha, M. Z. Virani, A. Monadjem, A. R. E. Sinclair, Another Continental Vulture Crisis: Africa’s Vultures Collapsing toward Extinction. Conservation Letters. 9, 89–97 (2016).

A. Santangeli, V. Arkumarev, N. Rust, M. Girardello, Understanding, quantifying and mapping the use of poison by commercial farmers in Namibia – Implications for scavengers’ conservation and ecosystem health. Biological Conservation. 204, 205–211 (2016).

Page last updated: 3/14/2021