Sampling environmental acoustic recordings to determine bird species richness

Abstract

Acoustic sensors can be used to estimate species richness for vocal species such as birds. They can continuously and passively record large volumes of data over extended periods. These data must subsequently be analyzed to detect the presence of vocal species. Automated analysis of acoustic data for large numbers of species is complex and can be subject to high levels of false positive and false negative results. Manual analysis by experienced surveyors can produce accurate results; however the time and effort required to process even small volumes of data can make manual analysis prohibitive. This study examined the use of sampling methods to reduce the cost of analyzing large volumes of acoustic sensor data, while retaining high levels of species detection accuracy. Utilizing five days of manually analyzed acoustic sensor data from four sites, we examined a range of sampling frequencies and methods including random, stratified, and biologically informed. We found that randomly selecting 120 one-minute samples from the three hours immediately following dawn over five days of recordings, detected the highest number of species. On average, this method detected 62% of total species from 120 one-minute samples, compared to 34% of total species detected from traditional area search methods. Our results demonstrate that targeted sampling methods can provide an effective means for analyzing large volumes of acoustic sensor data efficiently and accurately. Development of automated and semi-automated techniques is required to assist in analyzing large volumes of acoustic sensor data.

Efficient sampling of avian acoustic recordings: intermittent subsamples improve estimates of single species prevalence and total species richness

“…Another common aim of bioacoustics monitoring is to estimate the species richness of avian communities (Wimmer et al 2013, Towsey et al 2014. Here too, efficient means of detecting less common species are needed (Wimmer et al 2013).…”

Estimating population size of a nocturnal burrow-nesting seabird using acoustic monitoring and habitat mapping

“…Acoustic recording is a promising approach for many biodiversity assessments (Celis-Murillo et al 2012;Penone et al 2013;Sueur et al 2008;Wimmer et al 2013), and has been successfully employed to assess the changes in seabird breeding populations following island restoration (Buxton et al 2013). The number of recorded seabird vocalisations is expected to increase in larger colonies, but to our knowledge no attempt has been made to estimate absolute population size of a nocturnal burrow-nesting seabird species based on vocal activity rates measured from acoustic recordings.…”

Investigation of domain adaptation for acoustic frog species classification

“…Recently, advances in recording and storage technology provide a novel way to classify frog species. Compared to traditional field survey methods, the use of acoustic sensors greatly extend the spatiotemporal monitoring scale [13]. Therefore, large volumes of acoustic data have been collected from various locations.…”