Data from: Listening carefully: Comparing passive acoustic monitoring and conventional line-transect walks for monitoring breeding bird diversity in differently structured landscapes

Passive acoustic monitoring (PAM) of avian diversity has been developing rapidly in recent years. While the deployment of low cost and easy to apply devices in combination with classification algorithms brings many advantages, there is a knowledge gap on whether PAM is suitable for the monitoring of breeding birds. For conventional methods, breeding criteria are well established and contain repeated vocalisations during the peak mating season for most species. Here, we applied these criteria on PAM generated data to distinguish between breeding birds and nonbreeding species. We deployed six AudioMoth devices from end of March until June on each of nine golf courses in northern Germany. Differently structured sites were chosen to represent several habitat types. We used the BirdNet classifier to analyse the sound files and then verified results for each species at each site and applied the breeding criteria. Simultaneously, we conducted four conventional line transects at each site. Results showed a significant difference between both methods for overall detected bird species as well as breeding species. While on most golf courses the majority of species were classified as breeding with both methods, there were on average 12 more species classified as breeding by PAM than with the conventional method. Indicator species analysis revealed that especially breeding birds with subtle songs and calls were associated with PAM. With both methods, on average half of the detected species were classified as breeding. Our study presents an approach on how to further analyse PAM generated data for a differentiated ecological interpretation. We recommend developing breeding criteria for continuous monitoring with PAM, further research in detection probabilities, confidence score thresholds and measuring abundances for efficient monitoring schemes with PAM.