Aggressive Behavior, Intraspecific

Abstract

Aggression is commonplace in marine mammals. Males perform elaborate, ritualized threat displays, force copulations, fight and they commit infanticide. Females can also be aggressive in defense of themselves or their young. During aggressive encounters, marine mammals engage in a variety of agonistic behaviors including: vocal signals, facial expressions, body slaps, and stereotyped postures and movements. Overt fighting, with bites and chest slams, tail strikes or other direct body contact, occurs when disputes cannot be solved through the ritualized behavior route. Land breeding and female reproductive synchronicity select for extreme cases of sexual dimorphism, facilitate monopolization of resources correlated with fierce and bloody battles among males, and result in aggressive encounters that cause injuries and death. Marine mammals have impressive weaponry and secondary sexual characters related to agonistic tendencies, such as the tusks of walruses and narwhals, the snouts of some phocids and the manes of sea lions. The social life of marine mammals varies from very solitary to year-round interaction with many conspecifics, yet, in all cases, during breeding times, aggression escalates as an effective, although costly, way to resolve conflict.