The Development of the Navigational System in Young Homing Pigeons

Abstract

Bird navigation is generally looked upon as a two-step process described by Kramer’s map and compass model (1953). In step 1, the bird determines its home direction as a compass direction; in step 2, it uses a compass to localize this direction in space (cf. Wallraff 1974, Wiltschko W. and Wiltschko R. 1982). For both these steps, alternative mechanisms are available to the birds so that they can determine their home direction (1) by information obtained en route during the outward journey; or (2) by local information collected at the starting point of the return flight (in experiments: at the release site). In the first case, a simple strategy called route reversal is applied: the bird records the compass direction of the outward journey, integrating detours if necessary, and reverses this direction to obtain the homeward course (cf. Wiltschko et al. 1978). When using local information, we must assume that the birds make use of some kind of environmental gradients which form the grid of a “map”. Knowing the directions in which these gradients increase, a bird can extrapolate their values at unfamiliar locations, and so obtain its home direction by comparing the data of a given site with those of home (for details, see Wallraff 1974, Wiltschko W and Wiltschko R. 1982).