Black vultures cool off, stay clean and find dinner with surprising tricks
The American black vulture has no voice box, so it can only grunt and hiss. It has a poor sense of smell, so it tails turkey vultures, whose noses are keen, to find carcasses. And on hot days it keeps cool the way no sensible bird would: by streaking its own legs with droppings.
That last habit has a name, urohidrosis, and all New World vultures use it. As the moisture evaporates, it chills blood vessels running through the bare legs and feet, leaving white streaks of uric acid behind. Another cooling and cleaning trick is the spread-winged pose these birds strike on fence posts, thought to dry their feathers, warm them up and bake off bacteria. Storks and Old World vultures do the same.
Much of the bird's look is built for scavenging. Its glossy black plumage hides grime better than pale feathers would. The head and neck are bare, wrinkled grey skin, which stays cleaner when probing inside a carcass and gives parasites less to cling to, and many vultures bathe after a meal when water is handy. The nostrils are not separated by a wall of tissue, so you can see clean through the beak from the side. Disturbed, it may throw up, which both deters predators and lightens it for takeoff.
Despite the name, it is no close cousin of Eurasia's black vulture, an Old World raptor related to eagles and hawks. The American bird belongs to a separate family and is the only living member of its genus, whose name means raven-vulture. It sits at the base of a lineage including the turkey vulture that split off about 12 million years ago. A larger Ice Age form once lived across its range, and genetic work in 2022 showed that giant actually descended from the modern bird about 400,000 years ago, bulking up as it moved into high country, rather than the other way round.
Today its range runs from the northeastern United States to Chile and Uruguay, and it has been pushing farther north this century. Flocks roost together, often beside turkey vultures on bare dead branches.
Source: Black vulture
