These birds have evolved the lowest gastric pH in the animal kingdom.

These birds have evolved the lowest gastric pH in the animal kingdom, allowing them to digest diseased carrion and waste without becoming sick. In fact, species like the mountain-dwelling bearded vulture have stomachs so acidic, they can digest most bones in just 24 hours. This adaptation helps smaller vultures supplement their diet with dung, while larger vultures can consume diseased meat up to 3 days old. Their acidic stomachs protect them from living animals too: their rancid vomit scares off most predators.