sinking farther back, always at the point of being lost. Pictures are waxworks beside the passionate mobility of the living bird.
Female peregrines, known as falcons, are between seventeen and twenty inches long; roughly the length of a man’s arm from elbow to fingertip. Males, or tiercels, are three to four inches shorter, fourteen to sixteen inches long. Weights also vary: falcons from 1¾ to 2½ pounds, tiercels from 1¼ to 1¾ pounds. Everything about peregrines varies: colour, size, weight, personality, style: everything.
Adults are blue, blue-black, or grey, above; whitish below, barred crosswise with grey. During their first year of life, and often for much of their second year also, the younger birds are brown above, and buff below – streaked vertically with brown. This brown colour ranges from foxy red to sepia, the buff from pale cream to pale yellow. Peregrines are born between April and June. They do not begin to moult their juvenile feathers till the following March; many do not begin till they are more than a year old. Some may remain in brown plumage throughout their second winter, though they usually begin to show some adult feathers from January onwards. The moult may take as long as six months to complete. Warmth speeds it, cold retards it. Peregrines do not breed till they are two years old, but one-year birds may select an eyrie and defend territory.
The peregrine is adapted to the pursuit and killing of birds in flight. Its shape is streamlined. The rounded head and wide chest taper smoothly back to the narrow wedge-shaped tail. The wings are long and pointed; the primaries long and slender for speed, the secondaries long and broad to give strength for the lifting and carrying of heavy prey. The hooked bill can pull flesh from bones. It has a tooth on the upper mandible, which fits into a notch in the lower one. This tooth can be inserted between the neck vertebrae of a bird so that, by pressing and twisting, the peregrine is able to snap the spinal cord. The legs are thick and muscular, the toes long and powerful. The toes have bumpy pads on their undersides that help in the gripping of prey. The bird-killing hind toe is the longest of the four, and it can be used separately for striking prey to the ground. The huge pectoral muscles give power and endurance in flight. The dark feathering around the eyes absorbs light and reduces glare. The contrasting facial pattern of brown and white may also have the effect of startling prey into sudden flight. To some extent it also camouflages the large, light-reflecting eyes.
The speed of the peregrine’s wing-beat has been recorded as 4.4 beats per second. Comparative figures are: jackdaw 4.3, crow 4.2, lapwing 4.8, woodpigeon 5.2. In level flapping flight the peregrine looks rather pigeon-like, but its wings are longer and more flexible than a pigeon’s and they curl higher above the back. The typical flight has been described as a succession of quick wing-beats, broken at regular intervals by long glides with wings extended. In fact, gliding is far from regular, and at least half the peregrine flights I have seen have contained few, if any, glides. When the hawk is not hunting, the flight may seem slow and undulating, but it is always faster than it looks. I have timed it at between thirty and forty miles an hour, and it is seldom less than that. Level pursuit of prey has reached speeds of fifty to sixty miles an hour over distances of a mile or more; speeds in excess of sixty m.p.h. were only attained for a much shorter time. The speed of the vertical stoop is undoubtedly well over a hundred miles an hour, but it is impossible to be more precise. The excitement of seeing a peregrine stoop cannot be defined by the use of statistics.
Peregrines arrive on the east coast from mid-August to November; the majority reach here in late September and the first half of October. They may come in from the sea in any weather conditions, but are most likely to do so on a clear sunny day with a fresh north-west wind blowing. Passage birds may stay in one area for two to three weeks before going south. Return passage lasts from late February to May. Winter residents usually depart in late March or early April. Juvenile falcons are the first peregrines to arrive in the autumn, followed by juvenile tiercels, and later by a few adult birds. Most adults do not come so far south, but remain as close as they can to their breeding territory. This order of migration, which prevails along the European coastline from the North Cape to Brittany, is similar to that observed on the eastern coast of North America. Ringing recoveries suggest that immigrants to the east coast of England have come from Scandinavia. No British-ringed peregrines have been recovering in south-east England. Generally speaking, all the juveniles that wintered in the river valley, and along the estuaries, were paler in colour than juveniles from British nests; they had a distinctive wing pattern of light reddish-brown wing coverts and secondaries contrasting with black primaries, similar to that of a kestrel.
The territory in which my observations were made measures roughly twenty miles from east to west and ten miles from north to south. It was hunted over by at least two peregrines each winter, sometimes by three or four. The river valley and the estuary to the east of it are both ten miles in length. Together they formed a long narrow centre to the territory, where at least one peregrine could always be found. Why these particular places were chosen it is difficult to be sure. Most parts of England, including towns and cities, could provide a winter’s keep for a resident peregrine, yet certain areas have always been regularly visited, while others have been ignored. Peregrines that have a definite liking for duck or shore birds will obviously be found on the coast, at reservoirs and sewage farms, or in fenland. But the birds that wintered in the valley took a wide range of prey, in which woodpigeons and black-headed gulls predominated. I think they came here for two reasons: because this was a wintering place that had been used for many years, and because the gravelly streams of the valley provided ideal conditions for bathing. The peregrine is devoted to tradition. The same nesting cliffs are occupied for hundreds of years. It is probable that the same wintering territories are similarly occupied by each generation of juvenile birds. They may in fact be returning to places where their ancestors nested. Peregrines that now nest in the tundra conditions of Lapland and the Norwegian mountains may be the descendants of those birds that once nested in the tundra regions of the lower Thames. Peregrines have always lived as near the permafrost limit as possible.
Peregrines bathe every day. They prefer running water, six to nine inches deep; nothing less than two inches or more than twelve inches is acceptable to them. The bed of the stream must be stony or firm, with a shallow incline sloping gradually down from the bank. They favour those places where the colour of the stream-bed resembles the colour of their own plumage. They like to be concealed by steep banks or overhanging bushes. Shallow streams, brooks, or deep ditches, are preferred to rivers. Salt water is seldom used. Dykes lined with concrete are sometimes chosen, but only if the concrete has been discoloured. Shallow fords, where brown-mottled country lanes are crossed by a fast-running brook, are favourite places. For warning of human approach they rely on their remarkably keen hearing and on the alarm calls of other birds. The search for a suitable bathing place is one of the peregrine’s main daily activities, and their hunting and roosting places are located in relation to this search. They bathe frequently to rid themselves of their own feather lice and of the lice that may transfer to them from the prey they have killed. These new lice are unlikely to live long once they have left their natural host species, but they are an additional irritation to which the hawk is most sensitive. Unless the number of lice infesting the hawk’s feathers is controlled by regular bathing, there can be a rapid deterioration in health, which is dangerous for a juvenile bird still learning to hunt and kill its prey.
Though there can be many variations, a peregrine’s day usually begins with a slow, leisurely flight from the roosting place to the nearest suitable bathing stream. This may be as much as ten to fifteen miles away. After bathing, another hour or two is spent in drying the feathers, preening, and sleeping. The hawk rouses only gradually from his post-bathing lethargy. His first flights are short and unhurried. He moves from perch to perch, watching other birds and occasionally catching an insect or a mouse on the ground. He re-enacts the whole process of learning to kill that he went through when he first left the eyrie: the first, short, tentative flights; the longer, more confident ones; the playful, mock attacks at inanimate objects, such as falling leaves or drifting feathers; the games with other birds, changing to a pretence or attack, and then to the first serious attempt to kill. True hunting may be a comparatively brief process at the end of this long re-enactment of the hawk’s adolescence.
Hunting
