The effect of community on the territorial behavior of the threespot damselfish

Abstract

I examined the hypothesis that animals alter their behavior in response to changes at the community scale of organization, rather than simply reacting to a sequential set of independent interactions with other organisms. The focal species was the threespot damselfish, Stegastes planifrons,a territorial coral reef fish that experiences a high degree of variation in community composition. Field observations of individual threespot damselfish showed a significant increase in the amount of time spent on active territorial defense when the community contained greater proportions of food competitors. Territorial behavior also increased concurrently with higher species diversity in the community. However, no behavioral change was observed in response to the total number of fish entering the defended territory, suggesting that threespot damselfish are responding to more complex environmental cues associated with community structure rather than simple density.