BLACK VULTURE 37 



obliged to flap his wings from time to time. If the iip-currents are 

 strong, his need for flapping is reduced, but he never equals the grace 

 of the turkey vulture, I once compared the flight of the two birds 

 on a calm warm day in Georgia, as they were soaring over a sparse 

 pine forest. They were both about 60 yards above my head as I 

 reclined on the ground and about 40 yards over the forest. The 

 turkey vulture soared in small circles, neither rising nor falling and 

 without once flapping its wings, which with the tail were merely 

 adjusted from time to time to the air currents. The black vulture, 

 on the other hand, flapped its wings quickly at frequent intervals. 

 The contrast was very marked. After a while they both sailed off. 

 Whether they were inspecting me as possible carrion I do not know. 

 On another occasion, when lying outstretched on a sandy Florida 

 beach, I was startled by the shadow of a vulture passing over me 

 and at once sat up. I have been told that this is a habit of vultures 

 to determine whether a body is alive or dead. That they fly near 

 for this purpose is not improbable but one cannot believe that they 

 are able to plan to have their shadow fall on the body. 



When a black vulture flying and circling at a great height becomes 

 aware of a carcass lying far below it, the bird at first circles down 

 but soon drops with great swiftness, with legs hanging and, at 

 times, wings flapping furiously. Such actions of descent from a 

 height immediately attract the attention of other vultures on the 

 ground or roosting in trees and they at once follow up the clue. 

 One such action, even a mistaken one, can quickly collect a flock of 

 vultures. 



The question that has been much discussed then arises, as to how 

 these birds find the carrion. It is evident that sight is of great 

 importance, and the way in which vultures turn their heads in 

 flight suggests that they are all the time on the lookout for their 

 food. As carrion is so evident to our own sense of smell, even from 

 a great distance, it is natural for us to suppose that these birds also 

 are guided by the sense of smell, especially when trees or bushes 

 partly conceal the carrion. In fact, this belief in the use of the 

 smelling powers has always been a popular one, but since the experi- 

 ments of Audubon and Bachman (1835) it has generally been 

 accepted that sight alone guides the birds to their food. These 

 experiments, made chiefly on the black vulture, are summarized 

 briefly as follows : 



(1) A carcass securely hid in a brier and cane brake was not 

 detected by the birds, although the odor was very marked and 

 attracted dogs. 



(2) Carrion on ground covered by a frame of brushwood 12 

 inches above it was not detected by vultures who passed over it 

 during the 25 days of the experiment. 



