Intraspecific social information use in the selection of nest site characteristics

Animals commonly acquire information about the environment by monitoring how others interact with it. The importance of social information use probably varies among species. In particular, many migratory birds breeding in northern latitudes rely on social information provided by resident tits when making important decisions and are able to copy or reject selectively the decisions of tits exhibiting good or bad fitness correlates, respectively. However, little is known about the role of social information use among resident tits. In a field experiment we tested whether great tits, Parus major, given a choice between two novel alternative features on adjacent nest sites, copy or reject conspecific choice represented by a simulated tit nest nearby, when the nest exhibits a high or low fitness correlate (clutch size). In contrast to the results in the interspecific setting, the portrayed fitness of the simulated nest did not affect tits’ nest site choices. However, the age of males had an effect, irrespective of the fitness correlate. Pairs with an old male preferred, while pairs with a young male tended to reject, the nest site choices of the simulated previously settled conspecifics. This result is surprising, as the final nest site choice in this species is presumably made by females, whose age and other phenotypic traits did not have an effect here. Our results imply stronger influence of the male great tits on nest site choice than previously thought. Dominance relationships and intraspecific competition are possible explanations for the age-dependent patterns in social information use.