Homing of single pigeons--analysis of tracks.

The way in which homing pigeons find their home lofts is still obscure despite a long history of investigation. Since the work of Kramer & St Paul (1950a, 1952) and of Matthews (1951, 1953), it has been widely believed that some homing pigeons possess the ability to navigate. This belief is now based on the results obtained by many workers (see Schmidt-Koenig, 1965, for a critical review), which indicated that some pigeons arrived home from unfamiliar territory too quickly to be explained by their simply having searched for familiar landmarks. Other investigators found that pigeons released from unfamiliar locations showed an initial orientation toward the home loft. But there has always been a wide variation of the pigeons' homing times and a large scatter of the initial departure directions in such studies. This scatter has limited the usefulness of these data in deciding exactly what environmental cues were important for the pigeons' homing. In the belief that a knowledge of the pigeons' flight-path from release point to home might reduce this scatter and thus yield more information about the method the pigeons use to orient, Griffin (1952a) and Hitchcock (1952, 1955) used aeroplanes to follow visually the homeward flights of the pigeons. In their separate studies of small flocks of pigeons, both investigators reported that the pigeons were generally well oriented to the loft even in unknown territory. But the behaviour of a flock is always some unknowable consensus of the reactions of the individual birds and is thus difficult to analyse. Hitchcock (1955) reported following single pigeons visually by aeroplane but found that they frequently flew very erratically and often landed in trees. Because of the difficulty of keeping single pigeons in sight, the study did not provide conclusive information about the tracks taken by individual birds. Clearly, any real understanding of pigeon navigation must be based on what individual pigeons do on their flights home. Fortunately, the use of radio telemetry has enabled us to overcome many of the problems of following single pigeons. In this paper, we will report the results of tracking sixteen birds on 136 trips to their home loft, and we will discuss what these tracks imply about the pigeons' homing.