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How do birds orient over familiar terrain? In the best studied avian species, the homing pigeon (Columba livia), two apparently independent primary mechanisms are currently debated: either memorized visual landmarks provide homeward guidance directly, or birds rely on a compass to home from familiar locations. Using miniature Global Positioning System tracking technology and clock-shift procedures, we set sun-compass and landmark information in conflict, showing that experienced birds can accurately complete their memorized routes by using landmarks alone. Nevertheless, we also find that route following is often consistently offset in the expected compass direction, faithfully reproducing the shape of the track, but in parallel. Thus, we demonstrate conditions under which compass orientation and landmark guidance must be combined into a system of simultaneous or oscillating dual control. [ABSTRACT FROM AUTHOR]

Pigeons (Columba livia) display reliable homing behaviour, but their homing routes from familiar release points are individually idiosyncratic and tightly recapitulated, suggesting that learning plays a role in route establishment. In light of the fact that routes are learned, and that both ascending and descending visual pathways share visual inputs from each eye asymmetrically to the brain hemispheres, we investigated how information from each eye contributes to route establishment, and how information input is shared between left and right neural systems. Using on-board global positioning system loggers, we tested 12 pigeons' route fidelity when switching from learning a route with one eye to homing with the other, and back, in an A-B-A design. Two groups of birds, trained first with the left or first with the right eye, formed new idiosyncratic routes after switching eyes, but those that flew first with the left eye formed these routes nearer to their original routes. This confirms that vision plays a major role in homing from familiar sites and exposes a behavioural consequence of neuroanatomical asymmetry whose ontogeny is better understood than its functional significance. [ABSTRACT FROM AUTHOR]

In a recent paper,(1) we examined how experience of repeatedly flying with a specific partner influences pigeons' subsequent navigational decision-making in larger flocks. We found that pairs develop into a "behavioral unit" through their shared experience of joint flights, acquiring a single idiosyncratic route during training, and then forming spatially distinct subgroups when flying with other pairs. Further, differences between the route preferences of different pairs appear to be reconciled through the same mechanisms as those that apply to individuals. Here we examine in more detail the development of route preferences in pairs, as an example of "collective learning." We find that pairs acquire routes more quickly, but with less precision, than individuals. We use these results to hypothesize on the advantages and limitations of solving problems collectively.