A prelude to fighting during which the antagonists assess each other's fighting potential, by looking at weapons, body size, etc. Since such encounters can be won by bluff, there has often been an evolutionary trend towards exaggeration of weapons, etc. An example is the now extinct giant deer (Megalocerus giganteus) which had antlers measuring more than 3 m in span. These would have been very costly to produce (antlers are re-grown every year), and probably became too much of an energy burden as the climate became colder during the Ice Age. Modern deer assess rivals by means of roaring competitions. One stag usually retreats if the other can roar faster. A stag has to be in good condition to roar well, and this is probably a good indicator of fighting ability.
Similar ritualized contests are found in many species. Thus, some beetles engage in pushing matches, which the larger one usually wins, and male bighorn sheep (Ovis canadensis) charge each other and clash head on.
Subjects: Zoology and Animal Sciences.