Is difference in body weight, antler length, age or dominance rank related to the number of fights between fallow deer (Dama dama)?

Competitive interactions between mature male fallow deer were investigated to determine whether antler length, body weight, age or dominance rank were related to the number of fights between individuals. Four different hypotheses were tested; the first predicted that body weight and antler length indicate individual quality and, therefore, as the difference between competitors in body weight and antler length increases, there should be a corresponding decrease in fight rate. The second and third hypotheses predicted that, as difference in dominance rank increased there would be a decrease in fight rate between males either, as a risk reduction measure or because of inhibitory control by dominant males. A fourth hypothesis predicted that, where dominance rank does not mediate fight rate, that similarity between contestants based on age might be important. If this is the case, then as the difference in age between competitors increased there should be a decrease in fight rate. Our results show that when dominance rank is controlled for, there was no relation between body weight, antler length or age with fight rate. There was a negative relation between dominance rank difference and fight rate, a result that supports both the risk reduction and inhibitory hypotheses. There was an increasing tendency to fight with closely ranked males as cohorts reached peak reproductive age; males aged 5 yr fought with other 5-yr-old males based on rank difference and males aged 6 yr fought with other males aged six and across all age groups based on rank difference. This trend was not observed in 4 or 7-yr-old males. Our results suggest that males in prime breeding condition limit potential costs of fighting (such as time and energy) by only interacting with other males of similar rank.