Recent social experience, body weight and initial patterns of attack predict the social status attained by unfamiliar hens in a new group

To enhance understanding of processes determining social dominance, we quantified the contributions of existing individual characteristics and experience, and information obtained during initial encounters with new group members, on social status attained by hens (Gallus gallus domesticus) in a new group. We hypothesised that previous social experience (either with strangers or flock mates), body weight and comb size would be good predictors of a hen's aggressive behaviour and subsequent social status. Using structural equation modelling, we identified best-fit models to predict the outcome of combining unfamiliar individuals varying in these characteristics. In new triads of 150 red rock x light Sussex hens, hens with a relatively large comb and high body weight were more likely to have won a recent fight and performed more double attacks in their new group. Hens with recent experience of winning were more likely to attain the alpha position in the new group. In a second trial on new tetrads of 32 white leghorn hens, hens with a higher body weight performed more double attacks, leading to a higher rank in their new group. Hens that had recently been high ranking in their former social group also tended to perform more double attacks. Comb size and plumage condition were not good predictors of attack behaviour or rank in this trial. In both trials, a hen's body weight had predictive value in determining her attack behaviour and subsequent social status when introduced to a small number of strangers. We suggest that the timing and quality of social experience obtained prior to regrouping, the relative difference in comb size between opponents, and the absolute size and carriage of the comb (upright or floppy), influenced the efficacy of previous social experience and comb size as predictors of behaviour and rank in a new group.