More than 530 endangered vultures have been killed in northern Botswana after ingesting poison left by elephant poachers, the government said on Thursday, underscoring the broader ecological fallout from Africa’s illegal trade in ivory.
Five vulture species were identified at the site, which lies near Botswana’s border with Zimbabwe. Conservationists said that poachers had poisoned the birds in an effort to evade detection. As scavengers, vultures are attracted to freshly killed animals, and their presence in the air can alert rangers to poachers’ positions.
“Vultures are sentinels to poached animals, so they’re directly being targeted,” said Kerri Wolter, the founder and manager of VulPro, a nonprofit conservation group based in South Africa.
Poaching appears to be on the rise in Botswana, which is home to around one third of Africa’s elephant population and has long been regarded as a safe haven for the animals. A recent study estimated that over 385 elephants had been poached from 2017 to 2018, a lower total than in other parts of Africa but an alarming rise for Botswana, the scientists said.
In May, Botswana’s government lifted a five-year ban on trophy hunting, including on elephants, a decision that has been hotly debated both locally and in the international conservation community. Rural villagers say that elephants eat their crops and trample fields, a conflict that has undermined conservation efforts.
The discovery of the poisoned vultures this week drew fresh attention to the poaching problem. Among the dead birds were 468 white-backed vultures, the government said — a critically endangered species that was once widespread across the African continent. The government said that the vultures had eaten from three poisoned elephant carcasses.
Officials also counted 17 white-headed vultures, a species that has “undergone catastrophic declines,” with estimated population losses of 96 percent within three generations, according to the London-based Edge of Existence program.
As mobile and efficient scavengers, vultures play a critical role in ecosystems, and removing them can have wide-ranging impacts. In India, where vultures have all but disappeared, populations of rats and feral dogs have soared, raising fears of severe disease outbreaks.
Arjun Amar, an ornithologist at the University of Cape Town, said that vultures were facing a crisis in Africa, with many species declining precipitously over the last decade. Poisoning was by far the leading cause of mortality, Dr. Amar said, followed by electrocutions from collisions with power lines.
Vultures are often killed when farmers lay out poison meant for other animals. In some parts of Africa, vultures are hunted for use in traditional medicine. And so-called sentinel poisoning by poachers — likely the case with the vultures found dead this week — is a growing problem, Dr. Amar said.
In 2013, 400 to 600 vultures were poisoned from a single carcass in Namibia’s Caprivi Strip. A 2016 study recorded 11 instances of vulture poisoning by elephant poachers in Africa, leading to the deaths of more than 2,000 birds.
Officials in Botswana were decontaminating the area on Thursday, the government said in a statement, and samples had been sent for laboratory analysis.