Elephant seals of the Falklands

Male agonistic behaviour and dominance Male agonistic behaviour in southern elephant seals comprises two components, conventional assessment and direct aggression: both are very important in establishment and maintenance of dominance relationships. Assessment through visual and acoustic threats is more frequent than direct aggression and it is used to settle the most of the contests, especially between males with large differences in resource holding potential. Aggression through direct interaction with physical contact and long all out fight, although less frequent, is of crucial importance in the initial phase of settlement of dominance relationships between males with almost equal RHP.

Reciprocal head up display

Reciprocal pushing

Neck bite

Push and bite

Specific tactics and strategies of competition adopted by individual males are well correlated with both structural and behavioural phenotype. Variance in behavioural performance between males is very large, and larger than the one measured for simple structural traits. The specific breeding situation has a significant effect on the relationship between performance in competition and breeding success, but the same basic trend is apparent in all places. Results of agonistic interactions set up dominance hierarchies, and these hierarchies are long lasting and strongly linear, both at local and population level. Excellent performance in competition between males is a fundamental requisite to high breeding success, however the local variation of parameters like breeding sex ratio and density of competitors moulds the strength of this link: stochastic factors, and factors with a deterministic nature but almost unpredictable by individual males, change the rewards of effective competition tactics in different areas.

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