The impact of continuous variation in heritable personalities on
the social structure in the great tit (Parus major)

P.J. Drent

Netherlands Institute of Ecology (NIOO-KNAW), Heteren, The Netherlands

Great tits of both sexes show continuous variation in consistent phenotipically individual differences in exploration of a standard new environment (a gradual variation from fast to slow explorer). Although the absolute values of repeated tests varied with the year cycle, the inter-individual differences persist across time. This ‘exploration score’ is phenotipically correlated with many other behavioral traits related to coping with (environmental) challenges (e.g. boldness, risk-taking, aggressiveness, routine-formation, foraging patterns). Bi-directional selection and crossings experiments using a cross fostering design with guest-pairs show that these different behavioral traits are strongly genetically correlated. This all indicates a more general behavioural syndrome or coping strategy within the lifehistory of the species, comparable with the variation in human personality.

Hand-reared and wild birds were used in an array of experiments to study the impact of these personalities on the composition, structure and hierarchy in winter flocks with a scrounger producer character. The dominant-submission interactions between the members of a group were standard scored on and around a feeding table. Males dominated females. Males with territorial status and for females mating with a territorial male have the highest position in the rank. In the hierarchy of territorial males the nearby the territory the higher the position in rank and within that: faster explorer dominated slower ones. In mixed groups of age and status classes the time of presence and the personality determined the rank between non-territorial males whereby in contrast to territorial birds long present slow explores dominated fast ones. This is caused by impact of actions of (old) territorial males on the non territorial juveniles that is different for the different personalities.

Paper presented at Measuring Behavior 2005 , 5^th International Conference on Methods and Techniques in Behavioral Research, 30 August - 2 September 2005, Wageningen, The Netherlands.

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