Detection probability and abundance of a Long-eared Owl population in Switzerland

Traditional Long-eared Owl survey methods like auditory detection by fieldworkers are time-intensive and often yield uncertain results due to low detectability and observer bias. We analysed a large playback-assisted survey in the Canton of Zurich, Switzerland, using occupancy models. Surveys using playback were more effective than passive listening, as detectability was increased, while Tawny Owl presence reduced it. The best way to detect Long-eared Owls was to use playback during late March and early April. The combination of playback and occupancy modelling has led to a substantial reassessment of population size in our study area. Our findings emphasize the value of playback for optimizing survey methods for some species and provide essential baseline information for future studies and potential conservation actions.