Song rate and duetting in the Chirruping Wedgebill (Psophodes cristatus): frequency, form and functions

Much of our current understanding of song originates from studies of species living in seasonal environments, where breeding seasons are short and highly synchronised at the population level. By comparison, the form and function of song are less well understood in aseasonal environments, where breeding cycles are less predictable. We examined song rates of male and female Chirruping Wedgebills (Psophodes cristatus), a passerine endemic to the arid regions of inland, south-eastern Australia, across a 4 month period of breeding activity. Our results show that both males and females sing, and provide evidence of duetting. The song rate of male Wedgebills was highest in the early morning and during breeding and was substantially higher than the song rate of female Wedgebills. Over the course of the day, bouts of male singing were two orders of magnitude longer than females. By contrast, female song rate was independent of the time of day or reproductive phase. Females more often sang in tandem with their partners than expected by chance and duets occurred at a relatively low rate, independently of breeding phase. We discuss the possibility that male and female song and duets serve different functions.