Dana S Reid; University of Wisconsin-Madison;; Connor M. Wood, Sheila A. Whitmore, William J. Berigan, H. Anu Kramer, Nick Kryshak, John J. Keane, Sarah C. Sawyer, R. J. Gutierrez, Holger Klinck, M. Zachariah Peery

Vocal territory defense involves trade-offs with other life history demands, influencing territory size and thus resource partitioning and population density within a species. Here, we investigated how life history constraints affect territoriality and territorial vocal behavior in the California spotted owl (Strix occidentalis occidentalis) in the Sierra Nevada, California, USA, using high-resolution acoustic/GPS tags. We discovered significant differences in spotted owl vocal behavior and territoriality based on breeding status, with breeding owls with fledged young producing fewer and quieter territorial calls, calling within a restricted area around their nest location, and defending significantly smaller territories—but utilizing larger areas—than non-breeding owls. These results suggest that breeding spotted owls reduce their investment in territorial behaviors and spend more time rearing and provisioning offspring. Our finding that territoriality was strongly linked to breeding status has important ecological implications, suggesting that population density and space-use is fluid across the landscape even for a site-faithful, highly territorial species such as the spotted owl. Further, our results have key implications for passive acoustic monitoring programs and highlight the importance of using multiple call types, both territorial and non-territorial, to detect species of interest which may face similar vocalization constraints.

Spotted Owl Ecological Associations  Zoom Presentation