Pigeon homing: The influence of topographical features in successive releases at the same site.

A new device, the direction-recorder, offered the possibility to extend earlier studies of homing behaviour of pigeons when relevant topographical elements (mountains and large tracts of water) interpose between the release site and the home loft. Three series of experiments were carried out at three different sites to investigate intraindividual and interindividual variability in subsequent tosses from the same locality. Two release sites were chosen behind a mountain chain with respect to home; at the third site homeward directed route crosses the sea. From our results it turns out that homing pigeons may adopt different strategies. Moreover, a wide intraindividual variability was observed in repeated tosses at the same site; some pigeons remained faithful to the first route, whereas other birds tried successive new routes which, in most cases, were significantly shorter than previous ones. This result indicates that pigeons try, and are actually able, to improve their performance in subsequent releases from the same site.