Exploration, aggressive behavior and dominance in pair-wise confrontations of juvenile male great tits

In the development of social dominance, constitutional behavioural characteristics may play an important role apart from morphological traits. Previous work has shown that juvenile male great tits Parus major differ consistently in their early exploratory behaviour and can be classified as fast and superficial explorers or slow and thorough explorers. This study investigated whether these individual differences in exploratory behaviour are related to aggressive behaviour, and whether this affects dominance. In an experimental set-up, pair-wise fights were observed. The obtained data were corrected for possible influences of morphological traits. Consistent individual differences in aggressive behaviour were found, indicating that juvenile great tits can be characterised by that behaviour. Fast explorers started more fights than slow explorers, and birds that started more fights also won more fights. An additional experiment with pairs of fast and slow explorers confirmed that fast explorers won more fights than slow explorers. In conclusion, we demonstrated that individual differences in exploratory behaviour are related to aggressive behaviour, which affects dominance. The striking agreement of these findings with studies of rodents and pigs is discussed. It is suggested that the behaviour of fast explorers agrees with an active style of coping with stress, while the behaviour of the slow explorers resembles a passive coping style.