Large males

Often, male power struggles are settled by a test of strength, but if none of the parties retreats, fatal wounds could result. In the sexually active period, males are particularly confrontational and aggressive in the struggle to mate with females. Among many species, the males are bigger and stronger than the females. A male uses his size to demonstrate his power to other males and his attractive genes to females. The biggest male is often the dominant one, and it is usually he that wins most power struggles.

Among some species such as hippos, the dominant male tolerates smaller males in his territory, as long as they behave humbly. The territory is also the home of several females.

JOSEPH VAN OS/GETTY Elephants. The females live together in groups, and during the mating period, males fight for the right to mate with them.

WAYNE R BILENDUKE/GETTY Polar bears. There are about three males for every female in the rut, causing fierce fighting between males.