The Influence of Repeated Releases on the Homing Behaviour of Sand Martins (Riparia riparia)

Authors


Corresponding author: Prof. N. Emilio Baldaccini, Dipartimento di Etologia, Ecologia ed Evoluzione, Università di Pisa, via A. Volta 6, I-56126 Pisa, Italy. E-mail: bedini@discau.unipi.it

Abstract

Data on the effect of repeated releases on the homing behaviour of sand martins released four times from the same site (beyond 50 km from the nesting colony) are presented. The results, obtained by two series of releases, show a progressive improvement of both the initial orientation and the homing performances. When the birds released four times from the same site were displaced in a new site, located roughly at the same distance, but in the opposite direction to the former, they do not change directional preferences with respect to the last experimental release; the homing speeds were also not different to those recorded for birds without any release experience. While the learning of orienting cues can not be excluded, the data point out that the habituation to the handling stress and a form of directional training seem to play a major role in determining the observed behaviour. The familiarity with a site does not seem to improve the homing behaviour of sand martins when released from a different one.

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