Personalities in great tits, Parus major: stability and consistency

We carried out a longitudinal study on great tits from two lines bidirectionally selected for fast or slow exploratory performance during the juvenile phase, a trait thought to reflect different personalities. We analysed temporal stability and consistency of responses within and between situations involving exploratory and sociosexual behaviour. Exploratory behaviour was assessed both in the juvenile phase and in adulthood (2-3-year interval) by means of a novel object test and an open field test. We assessed agonistic behaviour twice in adulthood with a 7-month interval by confronting males with either a caged or a free-moving intruder. We assessed sexual behaviour in adulthood by presenting two caged conspecifics of the opposite sex. Exploratory scores still differed between the lines at both ages; however, slow birds became faster with age and were less stable than fast birds. Slow explorers spent more time in agonistic displays and took longer to attack than fast birds. Slow birds also took longer than fast birds to approach a member of the opposite sex. We conclude that, at the level of line, behavioural differences were stable over time and extended to other situations. At the individual level, consistency across time and situations was less evident overall, but fast birds tended to be more consistent than slow birds. Slow explorers could be described as reactive copers, showing a relatively high degree of behavioural plasticity, and fast explorers as proactive, in line with similar studies in rodents.