Vultures, including species from the Old World and New World, have incredibly long and wide wings. Many species are incapable of flapping for even short periods of time so they can become grounded during inclement weather. This past week in Colorado, we had multiple consecutive days of rainy weather. The result was when the weather cleared there was a large movement of Turkey Vultures, all of them gliding on rising air currents or thermals and heading south. While grounded, the Turkey Vultures are unable to feed so it was not surprising to see a flock of 9 birds feeding on a recent road-killed jackrabbit today. Turkey Vultures, unlike their close relative, Black Vulture, have a keen sense of smell and once fresh prey is found the spread out group lands to eat. Both Old World vultures and New World vultures, look-alikes but completely unrelated, have strongly hooked beaks which they use to tear open prey. Unrelated species (Old World and New World vultures) occupying the same niche is a good example of convergent evolution. Both Old World and New World vultures have bald heads, a necessity when sticking a head into a carcass where feathers would become covered in blood and guts.
Comparing New World and Old World vultures, our largest vulture is the endangered California Condor which compares in size with the largest African vultures, the griffon vultures. Medium-sized New World vultures include the South American King Vulture and the Old World counterpart, Lappet-faced Vulture. Surprisingly, our Turkey Vulture, while quite large, is in the small vulture group and compares with the Old World vultures such as Hooded Vulture and Egyptian Vulture. These small vultures usually do not congregate in large numbers at carcasses and both representatives specialize in taking skin and tough tissues such as sinews and tendons.
Turkey Vultures in Colorado need to migrate to warm weather countries for the winter for without thermals they would be unable to soar and therefore unable to find carcasses to eat. Black Vultures, a close relative of the Turkey Vulture, in Florida’s Everglades have “learned” that windshield wiper blades and the rubber seals around windshields are edible so visitors there are encouraged to use park-provided coverings for their cars.