I love vultures, and not just because they’re charismatic, intelligent, and physiologically incredible. No, I love vultures in a really sick way too. What they do when they feed on a carcass is repulsive but—let’s face it—it makes for fascinating viewing.

Vultures are the ultimate antihero: They’re ugly, aggressive, and have pretty rotten feeding habits. But they’re also one of the fastest declining families of birds in history—and that’s why National Geographic featured a story about them in the January 2016 issue.

Vultures are the world’s forgotten environmental disaster. Lions, elephants, and rhinos are in serious trouble—but vultures are arguably in more. In South Africa, for example, six of eight species in the country are endangered.

Vultures don’t