The Roaring of Red Deer and the Evolution of Honest Advertisement

In many large animals, changes in fighting ability within breeding seasons or across the lifetime of individuals are related to changes in body condition but not to obvious changes in size. In situations where a conflict of interests is likely to lead to a fight, we might consequently expect opponents to assess each other on traits which are related to variation in body condition. This appears to be the case among red deer stags. Competing stags engage in roaring ‘contests’ in situations where fights are likely. Observation combined with playback experiments showed that stags answered each others’ roars and that their roaring rate was related to that of their opponent. Both individual differences and temporal changes in roaring rates were correlated with changes in fighting ability and roaring contests usually occurred only where there was no obvious size discrepancy between opponents. The study suggested that assessment procedures probably continued during the parallel walks which commonly succeed roaring contests. © 1973, Brill. All rights reserved.