Nest size, nest building behaviour and breeding success in a species with nest reuse: the white stork Ciconia ciconia

Nest size and nest building behaviour affect individual fitness and thus, selection may act on these traits. Most data on nesting behaviour come from species that build a nest for each new breeding attempt, whereas almost nothing is known regarding nest reusers. Here, the association between nest size and nest building behaviour, and occupation date as well as breeding success of the white stork Ciconia ciconia, a migratory species with nest reuse, is presented. Large nests were occupied earlier and showed higher breeding success, even accounting for the confounding effect of the breeder's age. In addition, nest size increased steadily over the entire breeding season and only ceased when reproduction failed. However, this increase was not related to breeding success variables. Finally, nest size was related to the number of times that it was used in the past and thus, to the probability of successful reproduction. These results suggest that storks may seek and compete for bigger nests and that nest size could be an indicator of individual and/or nest-site quality.