ADJACENT NESTING AND EGG STEALING BETWEEN MALES OF THE GREATER RHEA RHEA-AMERICANA

In a three year field study on a population of 350 Greater Rheas Rhea americana we followed the fates of 138 nests. In four of these nests w e observed that, instead of one, there were two males sitting. These m ales were less than one metre apart and during the incubation period, they stole eggs from each other. There were no signs of aggression bet ween them. The total number of eggs in these adjacent or double nests was similar to that in single nests. Each double nest began as a singl e nest but during incubation, a second male sat beside the first male and started stealing eggs. We discuss possible functional and mechanis tic explanations of this apparently misdirected behaviour.