An Investigation of the Song Complexity of Toutouwai (Petroica longipes)

In this thesis, I examined the complexity of song repertoires in the endemic North Island robin (Petroica longipes), a highly territorial species. Focussing on the males of a robin population found in Zealandia, Karori Wildlife Sanctuary, I first tested the territorial function of song complexity by looking for evidence of the dear enemy effect (reduced aggressiveness in an individual’s response to neighbouring heterospecifics compared to non-neighbours) within my study population. There was a significant difference in the responses to neighbour and non-neighbour songs in a playback experiment, supporting the dear enemy effect. I then investigated the overall complexity of the songs of males within the study population by identifying and evaluating the phrases that they use within songs. I show that that North Island robins have rich song repertoires that appear to be stable across time for this population, based on data from 2015 and 2021/ 2022. However, based on the measures of song complexity used within my thesis, there is no evidence to support the hypothesis that more complex songs are correlated with a male’s reproductive success.