"It has been questioned whether the vulture discovers its food by means of the organ of smell or that of sight. I apprehend that its powers of vision are very considerable, and of most important use; but that it is principally from highly organized olfactories that it so speedily receives intelligence of where the savoury morsel is to be found, will plainly appear by the following facts. In hot climates, the burial of the dead commonly takes place in about twenty-four hours after death, and that necessarily, so rapidly does decomposition take place. On one occasion, I had to make a _post mortem_ examination of a body within twenty hours after death, in a mill-house completely concealed, and while so engaged the roof of the mill-house was thickly studded with these birds. Another instance was that of an old patient and much valued friend, who died at midnight; the family had to send for necessaries for the funeral to Spanish Town, distant thirty miles, so that the interment could not take place until noon of the second day, or thirty-six hours after his decease, long before which time--and a most painful sight it was--the ridge of the shingled roof of his house, a large mansion of but one floor, had a number of these melancholy heralds of death perched thereon, beside many more which had settled in trees in its immediate vicinity. In these cases, the birds must have been directed by smell alone, as sight was totally out of the question.
"In opposition to the above opinion, it has been stated by Mr. Audubon, that vultures and other birds of prey possess the sense of smell in a very inferior degree to carnivorous quadrupeds, and that, so far from guiding them to their prey from a distance, it affords them no indication of its presence even when at hand. In confirmation of this opinion, he relates, that he stuffed the skin of a deer full of hay, and placed it in a field; in a few minutes a vulture lighted near it, and directly proceeded to attack it, but finding no eatable food, he at length quitted it. And he further relates, that a dead dog was concealed in a narrow ravine, twenty feet below the surface of the earth around it, and filled with briers and high canes; that many vultures were seen sailing over the spot, but none discovered it. I may remark upon the above experiments, that, in the first case, the stag was doubtless _seen_ by the birds, but it does not follow that they might not also have smelt the hide, although inodorous to the human nose; in the second case, the birds had been undoubtedly attracted by the _smell_, however embarrassed they might have been by the concealment of the object which caused it. I have, in many hundred instances, seen the vulture feeding upon small objects under rocks, bushes, and in other situations, where it was utterly impossible that the bird could have discovered them but through the sense of smell; and we are to recollect, that the habit of the vulture is that of soaring aloft in the air, and not that of foraging upon the ground."