Description
These birds are generally large, ranging in length from the Lesser Yellow-headed Vulture at 56–61 centimeters (22–24 in) up to the California and Andean Condors, both of which can reach 120 centimeters (48 in) in length and weigh 12 or more kilograms (26 or more lb). Plumage is predominantly black or brown, and is sometimes marked with white. All species have featherless heads and necks. In some, this skin is brightly colored, and in the King Vulture it is developed into colorful wattles and outgrowths.
All species have long, broad wings and a stiff tail, suitable for soaring. They are the best adapted to soaring of all land birds. The feet are clawed but weak and not adapted to grasping. The front toes are long with small webs at their bases. No New World vulture possesses a syrinx, the vocal organ of birds, therefore the voice is limited to infrequent grunts and hisses.
The beak is slightly hooked and is relatively weak, compared with those of other birds of prey. It is weak because it is adapted to tear the weak flesh of partially rotted carrion, rather than fresh meat. The nostrils are oval and are set in a soft cere. The nasal passage is not divided by a septum (they are "perforate"), so from the side one can see through the beak, as in the Turkey Vulture. The eyes are prominent, and unlike those of eagles, hawks and falcons, they are not shaded by a bony brow bone. Members of Coragyps and Cathartes have a single incomplete row of eyelashes on the upper lid and two rows on the lower lid, while Gymnogyps, Vultur, and Sarcoramphus lack eyelashes altogether.
New World vultures have the unusual habit of urohidrosis, or defecating on their legs to cool them evaporatively. As this behavior is also present in storks, it is one of the arguments for a close relationship between the two groups.
Read more about this topic: New World Vulture
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