Long term consequences of interspecific cross-fostering in the wild

The significance of learning has been relatively overlooked in studies of fundamental behavioural traits such as species recognition, mate choice and social dominance. I propose a project to investigate long term consequences of interspecific cross-foster ing in the wild in terms of such behavioural traits. Since 1995, great tits and blue tits have been reciprocally cross-fostered in the field, providing unique data for investigating the consequences of interspecific cross-fostering. I will look at the po tential long term fitness costs of being cross-fostered in terms of survival and reproduction. Consequences for parental investment will also be considered. Further, I will investigate the species recognition and dominance of the offspring of cross-foster ed birds, also taking the sex of the cross-fostered parent into account. Three studies relate to song: first, how do cross-fostered males sing; second, how do the sons of cross-fostered males sing, and third, how does the song of cross-fostered males func tion in interactions with heterospecifics and conspecifics. I also propose a review article on early learning. This project may yield fundamentally new insights into the determinants of the development of species recognition and social dominance. Moreover , cross-fostering is used in conservation biology as a method to save endangered bird species, and unveiling its consequences in the field is of relevance to this practice.