Vocal behaviour of the Common Koel, Eudynamys scolopacea, and implications for mating systems

Abstract

The Common Koel, Eudynamys scolopacea, is a migratory cuckoo that occurs along the eastern coast of Australia. Its most conspicuous feature is the loud and persistent calling of males heard throughout the breeding season. Although the commonest vocalisation of the Koel, the Cooee call, is well known, other vocalisations have not been described in detail. Here we report on six vocalisations produced by adult birds, including duetting. The rate of calling of male Koels was investigated on two different scales: monthly over the breeding season, and hourly during the day and night. Calling peaked both in the early and late months of the breeding season, possibly associated with the availability of host nests. During the day, calling rates were significantly higher at dawn and dusk than at all other times of the day. Data collected on trees inhabited by Koels showed that calling males favoured trees with a particularly wide canopy and dense foliage; most often, these were species of Ficus. We speculate that the Koel shares with other cuckoos a basic breeding pattern based on male dominance interactions that lead to polygyny but that the discovery of duetting strongly suggests the possibility of short-term pair-bonding within this mating system.