Reproductores y dispersantes de una especie de larga vida, el búho real (Bubo bubo)Diferencias en el uso del espacio y patrones de movimiento de dos facetas de una misma población

Resumo

Social status can be reflected in many aspects of an individual’s behaviour and ecology, including habitat use and conspecific interactions. In territorial species where at least two social groups – breeding birds and non-territorial floaters – are recognized, the diverse tasks associated with territorial ownership can lead territory holders to behave differently from the non-territorial part of the population. Territory holders defend their breeding area and reproduce, whereas floating individuals are dispersing and lead a more transient life, during which they do not show any territorial behaviour even when settling in a more or less fixed area (known as the stop phase). As social interactions are based on visual and vocal cues, the use of specific sites for sending and ⁄ or receiving signals can be a crucial choice in an animal’s life. By analysing the post-site selection of Eagle Owl Bubo bubo breeders and floaters during their nocturnal activity, we found that: (1) territory holders selected more visible and dominant posts than non-territorial floaters; (2) the choice of posts made by floating individuals did not differ between the wandering and stop phases of dispersal; and (3) floating females intruded more frequently than floating males within a breeder’s home-range. These findings highlight the fact that two social strategies are possible within the same species, depending on an individual’s social status and its related tasks. Breeders could take advantage of visible locations to declare their status as territory holders, whereas floaters could benefit from a more secretive life to wander unnoticed among occupied territories. This secretive life would help floaters to reduce the risks associated with conspecific aggression. Finally, the greater occurrence of floating females within breeders’ home-ranges can be explained by the fact that female incursions in a breeder’s home-range are less risky than male intrusions.