Some aspects of the breeding behaviour of Peregrine falcons on Langara Island, B.C.
Creators: name: Nelson, Robert Wayne
Publisher: name: University of Calgary
Year: 1970
Subjects: subject: QL 696 A2 N44 1970
subject: Peregrine falcon
subject: Birds - Behavior

description: Bibliography: p. 289-296.
description: The behaviour of Peregrine 'Falcons (Falco ueregrinus pealei) in the breeding season was studied on Langara Island, in the Queen Charlotte Islands group of British Columbia in 1968, 1969 and 1970, for a total of almost twelve months .in the field. In 1968 one pair of falcons and their young was observed closely from coastal rocks and from a blind overlooking the nest ledGe at Area A. In 1969 another pair was studied in similar fashion at Area B. In all three years observations were made on several other pairs and their young. The Peregrine Falcon has a vocabulary of at least twelve separable calls. Adult Langara Island Peregrine Falcons appear not to migrate. In 1969 a pair was observed through the Preincubation Phase. The male seems to take the initiative at this period, stimulating the female by his flight behaviour, Ledge-demonstration displays and Male-ledge displays. If disturbed at a prospective nest ledge, the falcons my quickly abandon it in favour of another ledge some distance away. Transfers of food from the male to the female were first observed almost a month prior to egg-laying. Food-transfers are similar to those seen between adults and fledglings. During parts of courtship, the female exhibits nestling-like behaviour. The significance of markedly lethargic behaviour in the female prior to the laying of the eggs is discussed. During incubation, the majority of hunting is done by the male in twilight before dawn. During the daylight hours he retrieves food for himself and the female from caches on the cliff. Only the female incubates at night. Although the male plays a role in daytime incubation, the amount of time that he devotes to this is small. This is thought to be partly explained by his inability (due to his smaller size) to brood nestlings effectively. The female broods the nestlings for about a week after hatching, but continues to brood them at night for some time longer. When the nestlings become too large for this, the female continues a nightly 'guard duty' at the ledge. Feeding behaviour of nestlings gradually develops from a stage in which the parents feed the gaping young, through a stage in which the young take food from the parent's beak, to a stage in which food is sometimes forcibly seized from the parent. The young falcons first fly at 41-44 days of age, and become adept at flying within a week. From then on they receive most of their food from the parents in the air, usually by means of foot-to-foot Food-transfers. The parents frequently attempt to hide from their young for long periods. The fledglings 'play’ with each other and make play-attacks at inanimate objects, followed by mock-attacks at possible prey, and finally actual attempts to hunt for themselves. But they continue to be dependent on the parents for at least six weeks after first flying. The Langara Island falcons have been found to contain considerable amounts of chlorinated hydrocarbons. These are probably already affecting their ability to raise young, and possibly also some aspects of their behaviour.