Mark Cocker - The Peregrine - The Hill of Summer & Diaries - The Complete Works of J. A. Baker

Regular hunting over the same area will produce an increasingly effective defensive reaction from possible prey. It is always noticeable that the reaction of birds to a peregrine flying above them is comparatively slight in September and October, but that it steadily increases throughout the winter, till in March it is violent and spectacular. The peregrine has to avoid frightening the same birds too often, or they may leave the area altogether. For this reason he may be seen hunting in the same place for several days in succession, and then not be seen there again for a week or more. He may move only a short distance, or he may go twenty miles away. Individuals vary greatly in their hunting habits. Some hunt across their territory in straight lines five to fifteen miles long. They may suddenly turn about and fly back on the same course to attack birds already made uneasy. These hunting lines may run from estuary to reservoir to valley, and from valley to estuary; or they may follow the lines of flight from roosting places to bathing places. The territory is also effectively quartered by long up-wind flights, followed by diagonal down and cross wind gliding that finishes a mile or two away from the original starting point. Hunting on sunny days is done chiefly by soaring and circling down wind, and is based on a similar diagonal quartering of the ground. When an attack is made, it is usually a single vicious stoop. If it misses, the hawk may fly on at once to look for other prey.

In early autumn, and in spring, when days are longer and the air warmer, the peregrine soars higher and hunts over a wider area. In March, when conditions are often ideal for soaring, his range increases, and by long stoops from a great height he is able to kill larger and heavier prey. Cloudy weather means shorter flights at lower levels. Rain curtails the hunting range still further. Fog reduces it to a single field. The shorter the day the more active the hawk, for there is less time available for hunting. All its activities contract or expand with the shortening or lengthening of days on either side of the winter solstice.

Juvenile peregrines hover whenever the wind is too strong to allow them to circle sufficiently slowly above the area they are surveying. Such hovering usually lasts for ten to twenty seconds, but some birds are more addicted to the habit than others and will hover persistently for long periods. The hunting hawk uses every advantage he can. Height is the obvious one. He may stoop (stoop is another word for swoop) at prey from any height between three feet and three thousand. Ideally, prey is taken by surprise: by a hawk hidden by height and diving unseen to his victim, or by a hawk that rushes suddenly out from concealment in a tree or a dyke. Like a sparrowhawk, the peregrine will wait in ambush. The more spectacular methods of killing are used less often by juveniles than they are by adults. Some soaring peregrines deliberately stoop with the sun behind them. They do it too frequently for it to be merely a matter of chance.

Like all hunters, the peregrine is inhibited by a code of behaviour. It seldom chases prey on the ground or pursues it into cover, in the manner of other hawks, though it is quite capable of doing so. Many adults take only birds in flight, but juveniles are less particular. Peregrines perfect their killing power by endless practice, like knights or sportsmen. Those most adaptable, within the limits of the code, survive. If the code is persistently broken, the hawk is probably sick or insane.

Killing is simple once the peregrine has the advantage of his prey. Small, light birds are seized in his outstretched foot; larger, heavier birds are stooped at from above, at any angle between ten and ninety degrees, and are often struck to the ground. The stoop is a means of increasing the speed at which the hawk makes contact with his prey. The momentum of the stoop adds weight to the hawk and enables him to kill birds twice as heavy as himself. Young peregrines have to be taught to stoop by their parents; captive birds have to be trained by falconers in a similar way. The action of stooping does not seem to be innate, though it is quickly learnt. The ability to stoop at birds in flight was probably a comparatively recent evolutionary development, superseding capture by follow-chase and the taking of ground-game. Most birds still fly up from the ground when a peregrine passes above them, though this may increase their vulnerability.

The peregrine swoops down towards his prey. As he descends, his legs are extended forward till the feet are underneath his breast. The toes are clenched, with the long hind toe projecting below the three front ones, which are bent up out of the way. He passes close to the bird, almost touching it with his body, and still moving very fast. His extended hind toe (or toes – sometimes one, sometimes both) gashes into the back or breast of the bird, like a knife. At the moment of impact the hawk raises his wings above his back. If the prey is cleanly hit – and it is usually hit hard or missed altogether – it dies at once, either from shock or from the perforation of some vital organ. A peregrine weighs between 1½ and 2½ lbs.; such a weight, falling from a hundred feet, will kill all but the largest birds. Shelduck, pheasants, or great black-backed gulls usually succumb to a stoop of five hundred feet or more. Sometimes the prey is seized and then released, so that it tumbles to the ground, stunned but still alive; or it may be clutched and carried off to a suitable feeding place. The hawk breaks its neck with his bill, either while he is carrying it or immediately he alights. No flesh-eating creature is more efficient, or more merciful, than the peregrine. It is not deliberately merciful; it simply does what it was designed to do. The crow-catchers of Königsberg kill their prey in the same way. Having decoyed the crows into their nets, they kill them by biting them in the neck, severing the spinal cord with their teeth.

The peregrine plucks feathers from his prey before he begins to eat. The amount of plucking varies, not only with the hunger of the hawk, but also according to individual preference. Some hawks always pluck their prey thoroughly, others pull out only a few beakfuls of feathers. Peregrines hold the prey steady by standing on it, gripping it with the inner talon of one or both feet. Plucking takes two to three minutes. Eating takes ten minutes to half an hour, depending on the size of the prey; ten minutes for a fieldfare or redshank, half an hour for a pheasant or mallard.

Prey may be eaten where it falls, if it is too heavy to carry off, or if it has landed in a suitable place. Many peregrines seem to be quite indifferent, feeding wherever they happen to make a kill. Others prefer a completely open place, or a completely secluded one. Seventy per cent of the kills I have found were lying on short grass, although most of the land here is arable. Peregrines like a firm surface to feed on. Small kills are often eaten in trees, especially in autumn. Birds reared in tree nests may eat their kills in trees whenever possible. On the coast, some peregrines prefer the top of the sea-wall for feeding, others eat at the foot of the wall, near the water line. The latter may have come from cliff eyries and be used to a steep slope above them as they eat.

A peregrine kill can be easily recognised. The framework of a bird is left on its back, with the wings untouched and still attached to the body by the shoulder-girdles. The breast-bone and all the main bones of the body may be quite fleshless. If the head has been left, the neck vertebrae will usually be fleshless also. The legs and back are frequently left untouched. If the breast-bone is still intact, small triangular pieces will have been nipped out of it by the peregrine’s bill. (This is not always true of very large birds, which have thicker bones.) When a kill is left with a good deal of meat still on it, the peregrine may return next day, or even several days later, to finish it up. Surplus meat from abandoned kills helps to support foxes, rats, stoats, weasels, crows, kestrels, gulls, tramps, and gypsies. The feathers are used by long-tailed tits in the construction of their nests. I have found an unusual concentration of such nests in areas where many kills have been made.