Effect of Call Types on White-Breasted Waterhen (Amaurornis phoenicurus) Response to Playbacks on Pratas Island, Taiwan

The White-breasted Waterhen (Amaurornis phoenicurus) is the only bird species known to breed on Pratas Island, Taiwan, for the past few decades. Since they are secretive and very difficult to observe, responses to different call playbacks were tested experimentally in the field to determine if call type affects response of birds to improve future surveys. Playbacks of two different call types (advertising call and aggressive call) were carried out at 26 stations in the east region of the island in April, June, July, and August 2016. The frequency of response and behavioral reaction of waterhens to playbacks were recorded within a 6-min test period at each station. Playbacks of the advertising call elicited more responses at stations than did aggressive calls. Two-way Repeated Measures ANOVA revealed a significant difference in response frequencies for the main effect of call type, but no difference was found for monthly effect and an interaction term for call type and month. This study provides evidence that playback experiments of the advertising call during the courtship period can be an effective way to monitor the population size of a secretive species such as the White-breasted Waterhen.