Social status influences microhabitat selection: breeder and floater Eagle OwlsBubo bubouse different post sites

Abstract

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.

EFFECTS OF SOCIAL AND EXTRA-PAIR MATING ON SEXUAL SELECTION IN BLUE TITS (CYANISTES CAERULEUS)

“…Among others, it may influence territorial strategies (Campioni et al. ), social organization (Smith ), movement–settlement patterns (Petit ; Delgado et al. ; Mannan ), or the timing of reproduction (Hogstad ).…”

Shared space, individually used: spatial behaviour of non-breeding ravens (Corvus corax) close to a permanent anthropogenic food source

“…In either case, non-breeders are relatively difficult to study and, compared to breeders, little is known about the behaviour and intraspecific interactions of non-breeders or floaters (Smith 1978;Penteriani and Delgado 2011). This is surprising, since it is important to investigate the behaviour and ecological role of non-breeders in order to understand the structure and dynamics of a population and the evolution of the behavioural differences between social classes (Campioni et al 2010). Here, we define non-breeders as all non-breeding individuals, in contrast to the frequently used term ''floaters'', which includes only a fraction of sexually mature non-breeders.…”

Floater strategies and dynamics in birds, and their importance in conservation biology: towards an understanding of nonbreeders in avian populations

“…Under some circumstances a floater may shift from being a secretive presence within an occupied territory (Rohner, 1997;Delgado et al, 2009;Campioni, Delgado & Penteriani, 2010) to become an active intruder that seriously threatens the position of the 'owner' of the territory (Arcese, 1987). In such cases floaters can become a drain on breeders, mainly because: (1) owners may spend a great deal of time and energy chasing floaters from their territories (Sunde & Bølstad, 2004;Carrete, Don´azar & Margalida, 2006a), with floater intrusions representing an additional cost during reproduction (Birkhead, 1982;Sandell & Diemer, 1999;Pilz & Smith, 2004;Bretagnolle, Mougeot & Thibault, 2008); (2) high levels of floater pressure may oblige owners to reduce the sizes of their territories (Norton, Arcese & Ewald, 1982); (3) floaters may compete for food with territory owners; (4) in some species (notably raptors) the intruders can kill owners in territorial fights (Newton, 1979).…”