Fighting Strategies of Silvereyes, Zosterops lateralis.

Abstract

We examined the cost-benefit patterns of strategies used by Silvereyes initiating aggressive encounters against unfamiliar opponents at a localized food source. We recorded initiator behaviour of individually colour-banded birds at a feeding station on Heron Island, Great Barrier Reef, and found that, in crowded conditions where most fighting occurred indiscriminately, initiators used more threat elements than attack elements and that dominant and lower-ranking birds did not differ in their strategies when initiating encounters. This is in contrast to more attack-oriented initiator behaviour of captive birds fighting against familiar opponents. Between familiar members the initiator would use different strategies according to the rank of the opponent relative to the initiator. Our results indicated that birds fighting unfamiliar opponents would adopt strategies similar to those used against higher ranks by captive silvereyes, supporting the prediction of the cost-benefit hypothesis in agonistic encounters. SO - Journal of the Yamashina Institute for Ornithology