PhD project: Understanding the costs and benefits of individual variation in aggressiveness

Even within the same population, individuals differ markedly from one another in their behaviour. Although there is now overwhelming evidence for the wide-spread occurrence of such between-individual variation in behaviour, its evolutionary origin and maintenance remain largely unclear. I am interested in whether, and if so, how, individual variation in an ecologically relevant behaviour, territorial aggression, may mediate trade-offs among a suite of fitness-related traits in a wild population of a common bird species, the blue tit (Cyanistes caeruleus). The study site is located ca.12 km south of the city of Groningen in the Netherlands. Aggression is a key social behaviour expressed to monopolize vital resources such as food, territories and mates. It also bears severe costs such as high energy expenditure, injury or even death. I am specifically interested in how between-individual variation in male territorial aggressiveness may relate to variation in the quality of a male’s breeding territory, its siring success, its proneness to take risks, and its investment in parental care.