In some species, males directly compete with each other for access to females. (In those species in which males invest more in reproduction than do females, females may compete with each other for opportunities to mate with males.)

Bull Elk (Cervus canadensis
) competing for access to females.
Competition for mates need not involve outright combat, however. Very commonly, individuals (usually males, of course) engage in
courtship displays. These displays typically do two things: they identify the animal’s species (each species has a distinctive courtship display, which eliminates confusion), and they provide clues to the animal’s overall health and, therefore, it’s suitability as a mate. Females can choose mates based upon the quality of their courtship displays, and there is therefore no need for males to engage in potentially-dangerous combat to prove that they’re strong and healthy.

A male Superb Bird of Paradise (Lophorina superba
), seen from behind, performs
an elaborate and energetically-demanding courtship display while a female observes.