The sudden appearance overhead of this hawk produces an effect wonderful to witness. I have frequently seen all the inhabitants of a marsh struck with panic, acting as if demented, and suddenly grown careless to all other dangers; and on such occasions I have looked up confident of seeing the sharp-winged death, suspended above them in the sky. All birds that happen to be on the wing drop down as if shot into the reeds or water; ducks away from the margin stretch out their necks horizontally and drag their bodies, as if wounded, into closer cover; not one bird is found bold enough to rise up and wheel about the marauder--a usual proceeding in the case of other hawks; while, at every sudden stoop the falcon makes, threatening to dash down on his prey, a low cry of terror rises from the birds beneath; a sound expressive of an emotion so contagious that it quickly runs like a murmur all over the marsh, as if a gust of wind had swept moaning through, the rushes. As long as the falcon hangs overhead, always at a height of about forty yards, threatening at intervals to dash down, this murmuring sound, made up of many hundreds of individual cries, is heard swelling and dying away, and occasionally, when he drops lower than usual, rising to a sharp scream of terror.
Sometimes when I have been riding over marshy
H
The Naturalist in La Plata.
ground, one of these hawks has placed himself directly over my head, within fifteen or twenty yards of me; and it has perhaps acquired the habit of following a horseman in this way in order to strike at any birds driven up. On one occasion my horse almost trod on a couple of snipe squatting terrified in the short grass. The instant they rose the hawk struck at one, the end of his wing violently smiting my cheek as he stooped, and striking at the snipe on a level with the knees of my horse. The snipe escaped by diving under the bridle, and immediately dropped down on the other side of me, and the hawk, rising up, flew away.
To return. I think I am justified in believing that fear of hawks, like fear of men, is, in very nearly all cases, the result of experience and tradition. Nevertheless, I think it probable that in some species which have always lived in the open, continually exposed to attack, and which are preferred as food by raptors, such as duck, snipe, and plover, the fear of the falcon may be an inherited habit. Among passerine birds I am also inclined to think that swallows show inherited fear of hawks. Swallows and humming-birds have least to fear from raptors; yet, while humming-birds readily pursue and tease hawks, thinking as little of them as of pigeons or herons, swallows everywhere manifest the greatest terror at the approach of a true falcon; and they also fear other birds of prey, though in a much less degree. It has been said that the European hobby occasionally catches swal-lows on the wing, but this seems a rare and exceptional habit, and in South America I have
Fear in Birds. 99
never seen any bird of prey attempt the pursuit of a swallow. The question then arises, how did this unnecessary fear, so universal in swallows, originate? Can it be a survival of a far past--a time when some wide-ranging small falcon, aerial in habits as the swallow itself, preyed by preference on hirundines only?