Potentially, homing from distant areas can be based on two different principles of navigation: (1) A path-integration mechanism records and integrates an animal's motions during the outward trip; it is independent of location-specific stimuli. (2) Site localization, by contrast, is performed by deducing the animal's position in relation to home from such stimuli. Hence the first mechanism entirely depends on an uninterrupted flow of “outward-journey information”. The second mechanism may but need not be independent of stimuli recorded during the outward journey.

Homing of pigeons is evidently based on site localization. Empirical findings do not support the idea that in experiments using passive displacement path integration is involved in addition or alternatively. Also, there is no reason to assume that very young pigeons transitionally, for only few weeks, apply such a method (as has been concluded by Wiltschko & Wiltschko 1982, 1985, etc.).

It is shown that very young pigeons require local olfactory signals for initial homeward orientation as do older birds (Fig. 1). They are not generally better at homeward orientation than older inexperienced pigeons and show similar deviations from home and preferences for a particular compass direction (Table 1, Fig. 2).

Olfactory signals appear to be gathered, as good as conditions allow, during any stage of a homing experiment. No fundamental difference can be recognized between olfactory “outward-journey information”, “release-site information”, etc. Signals received at different times and sites before release may contribute by varying proportions to the initial-orientation patterns observed under varying circumstances.