Using autonomous recording units and change-point analysis to determine reproductive activity in an aerial insectivore

ABSTRACT Autonomous Recording Units (ARUs) are commonly used, alongside traditional methods, to study the presence/absence of vocal species. ARUs are useful in monitoring species that are secretive or vocalise at night. We endeavoured to develop a method to monitor avian reproductive activity using ARUs. Olive-sided flycatchers (Contopus cooperi), an at-risk passerine, are an ideal species with which to develop this method as they have a loud distinct call and have large territories without much intrusion from conspecifics. Olive-sided flycatchers have a distinct call pattern during the breeding season. We used a change-point analysis to determine the dates of significant changes in their call pattern to determine if individuals were successfully breeding. We monitored 22 Olive-sided flycatchers in central New Brunswick in 2018 and 2019. We found that using a combination of ARUs and change-point analyses was a viable method for studying reproductive activity of Olive-sided flycatchers. We found that 27% of Olive-sided flycatchers were successfully breeding which, when considering erroneous classifications, is within the range of nest success (30–65%) documented elsewhere. Our method shows promise for studying other bird species as well as other vocal non-avian species.