High rates of inbreeding among hooded vultures in Ghana and South Africa spell trouble for their future, according to a newly published study. The study found that despite wide differences in the population size of the birds in the two countries, both face similar risks associated with low genetic diversity. It underlined the need to protect hooded vultures (Necrosyrtes monachus) in both countries from hunting and habitat loss.
Researchers gathered molted feathers from vulture nests in Ghana, where this species is considered highly endangered due to rapid population declines but remains abundant for now, and in South Africa, where it’s estimated that only 100-200 mature adults remain, mostly in Kruger National Park.
Despite the variance in their overall population size, the birds in both countries showed high levels of inbreeding and low genetic diversity — a “troubling” finding, according to the authors.
The study showed that while the number of hooded vultures in South Africa is dwindling, there’s still a basis for their population to recover. “It still does have some unique genetic components which are important to conserve,” said study co-author Sandi Willows-Munro, an associate professor at the University of KwaZulu-Natal in South Africa.
Hooded vultures play a critical ecosystem role in both countries, scavenging on carcasses and thus removing disease and potentially harmful bacteria. Low rates of genetic diversity would mean that these populations are vulnerable to threats, such as disease outbreaks, and less adaptable to environmental change.
Researchers had initially thought that Ghana’s relatively large population of hooded vultures meant they would be genetically more diverse than their South African counterparts. But according to Willows-Munro, their findings suggest that the West African country’s population is “not doing so well” genetically. This could leave them highly vulnerable to disease outbreaks, such as avian flu.
The reason why Ghana’s hooded vulture population shows such high levels of inbreeding is unclear. One theory, Willows-Munro said, is that the species may have passed through a genetic bottleneck long ago, when it experienced a dramatic population decline due to climatic shifts as some of the country’s grasslands became forests.
It may also be due to a more recent phenomenon, caused by human-driven actions. It’s a question the research team is continuing to investigate and which it hopes to shed light on in future studies.
“The take-home message is that you can’t just count the numbers of vultures and populations and equate that to whether there’s a healthy population or not,” Willows-Munro said.
The price of losing vultures
Hooded vultures are considered critically endangered and are in the midst of a large population decline across their range. Like many other vulture species in Africa, they face an array of threats, including habitat loss, poisoning, collisions with electricity lines, and hunting for “belief-based use.”
These birds were once ubiquitous in Ghana, said study co-author Justus Deikumah, a conservation biologist with University of Cape Coast in Ghana and West Africa representative for the vulture specialist group at the IUCN, the global wildlife conservation authority. They species has become less abundant in recent decades due to a variety of pressures, Deikumah said, including their use in traditional medicine. Conservationists have recently launched a multiyear action plan specifically targeting this threat.
In South Africa, vultures are under pressure due to both intentional and unintentional poisoning, with their parts also used in traditional medicine. A study published in 2021 found that one single association of traditional health practitioners harvested as many as 800 vultures per year for such purposes in the Kruger to Canyons Biosphere Region.
For Johannes Masopa Mphelo, a sangoma or traditional medicine practitioner and president of the Traditional Healers Association of Southern Africa, the use of vulture parts comes from a misinterpretation of traditional medicine. “There is no way we can use vultures to heal or to generate medicine,” he said. “We’re only using herbs from the ground and only using parts from the trees.”
Mphelo, who is also a police officer, said that in his home region of Limpopo province, South Africa, the birds are poisoned by people who believe their parts can bring worldly success. “There is no such benefit of becoming rich or healing people with vulture parts,” he said. “It’s all a lie.”
In his view, losing vultures will harm South African communities. “If we kill vultures, what is it that we are going to have in the future? Because our children and our grandchildren will never know the vulture,” Mphelo said.
The decline in vulture populations may prove to have health impacts for those communities as well. By scavenging carcasses, vultures cleanse landscapes of corpses, thus removing harmful bacteria and diseases. A paper published earlier this year linked a precipitous decline of vulture populations in India to the deaths of more than 500,000 people between 2000 and 2005. These findings are cause for concern in Africa too, say experts such as Deikumah.
As vulture numbers decline, other scavengers such as feral dogs can increase. Unlike vultures, they can then act as disease reservoirs, potentially spreading rabies and other diseases. Research in Ethiopia, for instance, found that as vulture numbers visiting abattoirs fell, dog numbers doubled, potentially increasing the risk of rabies for local communities.
Studies directly linking vulture declines to the spread of disease in Africa are lacking, but experts say such scenarios could easily play out.
“It’s really important that that we preserve these species because they give us such an important sanitation service,” Willows-Munro said. “In South Africa, where we have huge vaccination campaigns against rabies, we still have a big problem. In other countries that have less-established vaccination programs, I can imagine the impact is going to be even worse.”
Curbing the threats
Researchers say there’s a number of steps governments and communities could take to protect vultures and counteract the diminishing genetic diversity found in South Africa and Ghana. They propose captive breeding, reintroductions, supplementary feeding, GPS tracking to better understand population movements, and ongoing genetic monitoring.
André Botha, co-chair of the IUCN’s Vulture Specialist Group, said the study could help spur conservation action. “It highlights the need for conservation action in the peripheral populations, or the edge populations, within South Africa,” he told Mongabay.
The study also underlines the need for far greater protection for the birds in Ghana, and West Africa more broadly, where threats are high.
Mphelo said that in South Africa, raising awareness of the precarious position the birds are in could help combat the practice of hunting them for traditional medicine uses.
“People need education. They need to be educated about the importance of vultures for nature,” he said. “Because vultures have also got a right to life.”
Citations:
Le Roux, R., Colmonero-Costeira, I., Deikumah, J. P., Thompson, L. J., Russo, I. M., Jansen van Vuuren, B., & Willows-Munro, S. (2024). High conservation importance of range-edge populations of hooded vultures (Necrosyrtes monachus). Scientific Reports, 14(1). doi:10.1038/s41598-024-68756-2.
Mashele, N. M., Thompson, L. J., & Downs, C. T. (2021). Uses of vultures in traditional medicines in the Kruger to Canyons Biosphere Region, South Africa. Journal of Raptor Research, 55(3). doi:10.3356/jrr-20-36.
Frank, E., & Sudarshan, A. (2023). The social costs of keystone species collapse: Evidence from the decline of vultures in India. SSRN Electronic Journal. doi:10.2139/ssrn.4318579.
This article by Sean Mowbray was first published by Mongabay.com on 16 September 2024. Lead Image: Two hooded vultures in the Gambia. Image by Roger Sanderson via Flickr (CC BY-NC 2.0).
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