Saturday, March 15, 2014

Black Vulture

The BirdsEye folks have a companion app for the iPhone that maps birding hotspots. Thus I learned of Ray Roberts State Park near Denton, Texas, complete with a “resort” at which one might spend the night. Really the resort is a motel stuck in the middle of the park, a very clean and convenient location, but lacking in the accouterments one normally associates with the word “resort.” But birders need only birds.
Roosts are important for Black Vultures. Adults aggressively control roost membership, and generally non-related birds are barred from membership. This exclusivity allows birds to locate carcasses by following successful birds to food sources. Being related means this mentorship is not at the genetic (and hence evolutionary) disadvantage to the tutor.
Black Vultures do not build nests. They lay their eggs on the ground, in caves, hollow trees, or abandoned buildings. They are monogamous and form long-term bonds. They feed their young for up to eight months after fledging. Most of the information reported in this post is from Buckley (1999).
Black Vultures are almost exclusively carrion eaters. Unlike the Turkey Vulture, which use olfaction to locate dead animals, Black Vultures lack a sense of smell and can not find carrion by scent alone. (In Ecuador, I have seen Turkey Vultures locate rotten meat completely hidden in beetle traps.) Black Vultures make up for this inability to locate food by smell by following Turkey Vultures and then displacing them at the feeding site. In the photo below, taken at the Aransas National Wildlife Refuge, the Black Vulture on the right seems to be keeping a close watch on the two Turkey Vultures on the left.

No comments:

Post a Comment