UBC Theses and Dissertations
Aggressive behaviour, territoriality, and parental success in three-spined sticklebacks Black, William Robert
Male three-spined sticklebacks without territories cannot reproduce; and in order to establish and maintain a territory, a male must behave aggressively toward other fish. Such social organization raises questions about determination of the size of the breeding population and the selective advantage of particular levels of aggressive behaviour. Experiments varying the amount and kind of social contact with other fish showed some of the effects of social organization. Grouped males build nests sooner, and hatch a smaller proportion of clutches of eggs than isolated males. Fry survive less well with grouped males. There are consistent differences between individual males in aggressiveness during the reproductive cycle. Changes in aggressive behaviour and territory size have similar U-shaped temporal patterns which are common to all males. Aggression is lowest and territory size smallest just before the clutch hatches when the male spends most time fanning. Males without clutches sometimes attack the nests of other males. Interference by these males is often responsible for hatching failure. Individuals that hatch clutches seem no more aggressive than those that do not. However, males hatching clutches have larger territories during the first part of the reproductive cycle. They spend more time at the nest, and tend to remain closer to it.
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