Territoriality in diurnal raptors: relative roles of recent evolution, diet and nest site

Animal territoriality, defined here as defence of well-delimited breeding areas to exclude competitors, has been widely studied. However, the phylogenetic and ecological characteristics influencing the variation in the expression of this behaviour are poorly understood. We evaluated the effect of phylogeny and key ecological factors on territorial behaviour and territory size in diurnal raptors from the western Palearctic and New World. To our knowledge, our work is the first comparative analysis of raptor territorial behaviour and territory size that accounts for phylogenetic relationships. One important finding is that territorial behaviour has not been strongly conserved across evolutionary time, but differences in territoriality of diurnal raptors have been influenced by recent evolution, which has led to variations of this behaviour in response to changes in climate and habitat. Raptor current ecology is also associated with the expression of these traits. Species that capture more agile prey and nest in more protected sites were most likely to be territorial. Additionally, territorial species that are bigger and capture more agile and bigger prey defended larger territories than species feeding on more vulnerable and smaller prey. We discuss potential mechanisms for these patterns and the implications of our findings for future research on avian territoriality.