Three lions died this week in southwestern Kenya after eating a poison-laced cow carcass, Wildlife Watch reported. Those lions, and five others also poisoned, come from Masai Mara National Reserve’s Marsh Pride, which starred in the popular BBC series called Big Cat Diary.
The lions might be the best known victims of this incident, but they’re not the only ones. Eleven endangered white-backed vultures also died after feasting on poisoned carcasses—and these deaths underscore a huge problem. In Africa and elsewhere, poison has contributed to the population decline of these scavengers, whose importance is often overlooked because of their perceived ick factor.
“Across the board, it’s the biggest threat worldwide,” says Darcy Ogada, assistant director of African programs for The Peregrine Fund, an Idaho-based nonprofit dedicated to saving birds of prey. She's the author of a study published in June that attributed more than 60 percent of 7,800 vulture deaths recorded across 26 African countries to poisoning.
The populations of eight of the continent’s vulture species have fallen by an average of 62 percent, the researchers found, and four of Africa’s species are considered critically endangered by the International Union for Conservation of Nature, which determines the conservation status of the world’s animals.
Much of the time, vulture poisonings in Africa are unintentional. In this most recent instance, it’s believed that Maasai herders intended to poison the lions in retaliation for their attacks on livestock.
In some cases, however, ivory poachers use poison to kill elephants or lace their carcasses specifically to eliminate vultures so they won’t circle overhead and reveal the poachers’ presence. A study published Monday in the journal Oryx revealed that between 2012 and 2014, about 150 elephants and more than 2,000 vultures were killed in nearly a dozen poaching-related incidents in seven African countries.
It's not only vultures in Africa that die from poisoning. In Asian countries such as India, cultural attitudes contributed to a mid-1990s population plunge described as the “Asian vulture crisis.” Hindus revere cattle, Ogada says, so deadly sick cows were given diclofenac, a painkilling drug, to ease suffering. But diclofenac can kill the vultures that feed on dead cows. The drug is also used in Spain, home to 95 percent of Europe’s vulture population, according to The Guardian. And in North America, lead poisoning from spent ammunition in scavenged carcasses still threatens California condors (yes, they’re vultures), whose numbers have been growing since 1987, when the species went extinct in the wild.
Although they’re not winning any popularity contests, vultures are ecologically important. Their highly evolved digestive systems allow them to eat diseased carcasses and not get sick. Without them there’s a greater chance that disease could spread, Ogada says, because other scavengers such as hyenas or, in the case of urban settings, feral dogs, aren’t as well adapted.
That’s what happened in India, where feral dogs replaced vultures as the main scavengers, and rabies cases exploded. David Allan, curator of birds at the Durban Natural Science Museum, told National Geographic in July that because of that, health care costs climbed by an estimated $34 billion in India between 1993 and 2006.
But Ogada thinks there’s reason to love the birds beyond this service: “They’re cool. They’re squabbling, they’re kicking—they’re so charismatic,” she says.
Unfortunately for vultures in Masai Mara Reserve, human-lion conflict has been on the rise as land subdivisions and privatization reduce grazing land for cattle. At night, some Masai are known to allow their cattle into the reserve, where the grazing is better—and illegal, explained Anne Kent Taylor, a conservationist at the reserve and a National Geographic Big Cats Initiative grantee.
In this week’s incident, a pesticide in the highly toxic carbamate family likely killed the vultures and lions, though the poison won’t be revealed until lab testing concludes. Carbamates such as carbosulfan and carbofuran, which is banned in the European Union and effectively banned in the United States, have often been used to poison wildlife.
In 2009, though, the Philadelphia-based manufacturer of carbofuran, marketed under the trade name Furadan, held a buyback program to remove the product from Kenya after CBS’s 60 Minutes linked it to lion deaths in Masai Mara.
African countries need to curtail the easy access to highly toxic pesticides and other poisons, Ogada believes. “The abuse of pesticides goes far beyond poisoning wildlife,” she says in a National Geographic blog post.
This story was produced by National Geographic’s Special Investigations Unit, which focuses on wildlife crime and is made possible by grants from the BAND Foundation and the Woodtiger Fund. Read more stories from the SIU on Wildlife Watch. Send tips, feedback, and story ideas to firstname.lastname@example.org.