Behaviour 2019
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Foraging site fidelity and movements change according to breeding stage in a colonial bird of prey
Samuele Ramellini1, Simona Imperio2, Jennifer Morinay2, Federico De Pascalis1, Catoni Carlo3, Morganti Michelangelo4, Rubolini Diego1, Cecere G. Jacopo2. 1Dipartimento di Scienze e Politiche ambientali, Università degli Studi di Milano, Milano, Milano, Italy; 2Area Avifauna Migratrice, Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), Ozzano Emilia, Bologna, Italy; 3Ornis Italica, Roma, Roma, Italy; 4Consiglio Nazionale delle Ricerche – Istituto di Ricerca sulle Acque (CNR-IRSA), Brugherio, Monza-Brianza, Italy

In several animal taxa, it has been observed that some individuals may have a consistent use of specific foraging locations that are quite distinct from those used by other individuals of the same population: the so-called individual foraging site fidelity. We analyzed 505 foraging trips from 45 GPS-tracked breeding lesser kestrels (Falco naumanni) to assess the individual repeatability in movement behaviour, as well as the foraging site fidelity of breeders, during both incubation and nestling-rearing stages. We found that birds were repeatable in both foraging trip and foraging phase (outward, foraging and inward) metrics, consistently travelled along similar flight routes when targeting foraging grounds, and showed a high individual foraging site fidelity. Overall, repeatability and foraging site fidelity were higher during nestling-rearing compared to incubation, likely as an adaptation to deal with the higher energy demand stage, with a view to the optimal foraging theory. By consistently exploiting well known sites, if productive enough, breeders might indeed increase their foraging efficiency, shortening the time for food searching and optimizing nestling-provisioning.