Nearly 1,000 vultures have died in Guinea-Bissau since February of this year, many of them critically endangered hooded vultures, according to a statement released by the Vulture Conservation Foundation. Local authorities reported that the vultures “were bubbling from their beaks while dying” and “seemed to search for water,” the press release notes, suggesting that the birds may have been poisoned.

“This is, without any doubt, the worst case of vulture mortality in recent history that we know of,” says José Tavares, director of the Vulture Conservation Foundation, in remarks to Gizmodo. “The hooded vulture is a critically endangered species and while rarer in eastern and southern Africa, western Africa is its stronghold,” Tavares tells Mongabay. “Losing so many birds in its stronghold is a major blow to the species.”

The dead vultures were found in clusters on the outskirts of towns,...

The IUCN Red List categorizes hooded vultures (Necrosyrtes monachus) as critically endangered and reports that the species has declined by 83 percent over three generations (a time span of 53 years).

Strychnine is one possible source of the poisoning, reports The Guardian, which is used in Africa to control populations of feral dogs that feed on garbage dumps. Elsewhere on the continent, “sentinel poisoning,” in which poachers lace big game carcasses with arsenic or pesticides to prevent circling vultures from alerting rangers of an illegal killing, also poses a significant threat, according to the Raptor Taxon Advisory Group.

Mongabay reports that in Africa, nearly two-thirds of vulture deaths are caused by poisoning, while just under one-third of deaths are due to “belief-based practices” that place value on certain body parts, and almost one-tenth of deaths are due to electrocution.

“Electrocutions aren’t going to wipe out vultures. [But] poisoning will send them into extinction in Africa,” Campbell Murn, the head of conservation and research at the Hawk Conservancy Trust, tells Mongabay.

Tavares tells Mongabay that “indiscriminate poisoning is not the answer. There are other ways of dealing with dangerous animals that do not have such an impact on other species, for instance, shooting, trapping, maybe even targeted poisoning,” though he also notes that these methods are more expensive and more difficult to carry out.

Murn and other researchers are studying how vultures factor into the ecology of anthrax, botulism, and other diseases, according to Mongabay, with the goal of determining whether vultures play a critical role in reducing disease spread. 

“In some areas of Africa, vulture populations are in free fall,” Murn tells Mongabay. “If nothing changes, we could see vultures effectively disappear from the continent in a few decades.”

Amy Schleunes is an intern at The Scientist. Email her at aschleunes@the-scientist.com.

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