Illuminating The Nocturnal Habits Of Owls With Emerging Tagging Technologies

Owls play important cultural, ecological, and indicator roles throughout the world. Yet owls' cryptic behavior has led to uncertainties about their basic ecology, including foraging, communication, and functional roles within the community, and potentially hindered the implementation of effective conservation measures. Here we demonstrate the potential for next-generation GPS tags capable of recording high-precision, minute-by-minute locations paired with other technologies to resolve some of these uncertainties. We combined high-precision GPS tagging data with infrared (IR) video recorded by arboreally-mounted cameras at 5 spotted owl (Strix occidentalis) nest sites in the Sierra Nevada, USA to provide a uniquely detailed examination of owl foraging patterns. Our approach allowed us to identify the precise time and location of 54 predation events and prey identity. We also used high-precision GPS tags with on-board audio recorders to map the vocal activity of 8 individuals by matching the time of vocalizations in the audio data to GPS locations recorded at one-minute intervals. The combined spatial and acoustic data revealed that nonbreeding males had the most widespread territorial vocal activity (i.e., producing 4-note territorial calls), while females provisioning fledglings displayed extensive nonterritorial vocal activity (i.e., producing many contact calls). Thus, the GPS-tag technologies we employed can provide opportunities to better understand owl foraging, communication, territoriality, and population dynamics. The methods we describe are time- and resource-intensive but can be paired with techniques that are more applicable at landscape scales, such as stable isotope analyses, LiDAR-based habitat analyses, and passive acoustic monitoring to link local processes to broad-scale ecological patterns. Therefore, our approach could be applied to many species whose behavior inhibits direct observation. (c) 2021 The Wildlife Society.