I began working with Spotted Owls in 2016 as a PhD student with Zach Peery at the University of Wisconsin-Madison. Our collaboration – and that project – have continued to this day, and the footprint of our work has grown substantially, encompassing the entirety of the Spotted Owl’s range in California.
A note on taxonomy & status. Two subspecies of Spotted Owl live in California, the northern Spotted Owl (NSO; historically distributed from southern British Columbia to Marin County north of San Francisco) and the California Spotted Owl (CSO; distributed across the Sierra Nevada, Southern California, and into the Baja peninsula of Mexico). The NSO is federally endangered. The U.S. Fish and Wildlife Service recognizes two “population segments” of the CSO; the Sierra Nevada segment will be listed as Threatened, while the Southern California/Coastal segment will be listed as Endangered.
Check out the latest news here.
Sierra Nevada
The focus of my dissertation was the development of a landscape-scale acoustic monitoring program in the northern Sierra Nevada. Until then, Spotted Owl monitoring had been conducted small study areas, albeit with very detailed mark-recapture methods. I implemented a passive acoustic survey approach that allowed us to triple the spatial coverage of the nearest conventional study. This broad spatial coverage was essential to understanding the progression of the ongoing invasion of Barred Owls, as well as to allow for more robust inferences about the spotted owl population.
The first major finding of the project was that the Barred Owl population was growing rapidly in the northern Sierra Nevada. This finding, in turn, motivated a highly collaborative ecosystem-scale removal effort – which has so far proved to be a lasting success. In parallel, in 2023 we have provided the first-ever Sierra-wide population estimate for the California Spotted Owl. That analysis relied on the full Sierra Nevada PAM coverage that we first achieved in 2021, and we then linked that owl data with a novel forest disturbance dataset to reveal how fire, drought, and forest management are influencing the Spotted Owl.
In early 2026 we showed that the four-year population trend of Spotted Owls across the Sierra Nevada as derived from the acoustic monitoring program matched that of previous localized mark-recapture studies, vindicating the results of our initial power analysis.
At present, our Spotted Owl research efforts are concentrated on extracting more biological detail from the audio data. Our work in 2020 showed that we could use acoustic data to model the presence of owl pairs, a substantial improvement on simple detection/non-detection classifications; we are now pursuing that at much greater spatiotemporal scales. We have also begun work on individual identification. Both avenues have the potential to recover some of the demographic information that was lost when mark-recapture techniques were replaced with passive acoustic monitoring.
Northern California
Barred Owls remain an urgent threat to the northern Spotted Owl, and I am collaborating with the UW team led by Dr. Zach Peery in their work in California’s coastal redwood region to understand how we can effectively monitor – and control – the Barred Owl population in what appears to be the last stronghold of the northern Spotted Owl.
Our work has relied on passive acoustic monitoring to document the growth of the Barred Owl population in northern California, and on real-time acoustic monitoring to triage removal efforts.
Southern California
…pending…
Representative Publications
- Kelly, KG, CM Wood, KA McGinn, HA Kramer, SC Sawyer, SA Whitmore, DS Reid, S Kahl, A Reiss, J Eiseman, W Berigan, JJ Keane, P Shaklee, L Gallagher, H Klinck, RJ Gutiérrez, and MZ Peery. Estimating population size for California spotted owls and barred owls across the Sierra Nevada with bioacoustics. Ecological Indicators 154: 110851.
- Watson, WA, CM Wood, KG Kelly, DF Hofstadter, KF Kryshak, CJ Zulla, V O’Rourke, JJ Keane, RJ Gutiérrez, and MZ Peery. 2023. Passive acoustic indicates Barred Owls are established in northern coastal California and management intervention is warranted. Ornithological Applications duad017.
- Hofstadter, DF, NF Kryshak, CM Wood, BP Dotters, KN Roberts, KG Kelly, JJ Keane, SC Sawyer, PA Shaklee, HA Kramer, RJ Gutiérrez, and MZ Peery. 2022. Arresting the spread of invasive species in continental systems. Frontiers in Ecology and the Environment. doi: 10.1002/fee.2458.
- Reid, D, CM Wood, SA Whitmore, WJ Berigan, JJ Keane, SC Sawyer, PA Shaklee, HA Kramer, KG Kelly, A Reiss, RJ Gutiérrez, H Klinck, MZ Peery. 2021. Noisy neighbors and reticent residents: Distinguishing resident from non-resident individuals to improve passive acoustic monitoring. Global Ecology and Conservation. e01710.
- Wood, CM, RJ Gutiérrez, JJ Keane, and MZ Peery. 2020. Early detection of rapid Barred Owl population growth within the range of the California Spotted Owl advises the Precautionary Principle. The Condor 122: 1-10.
- Wood, CM, SA Whitmore, RJ Gutiérrez, SC Sawyer, JJ Keane, and MZ Peery. 2018. Using metapopulation models to assess species conservation – ecosystem restoration trade-offs. Biological Conservation 224: 248-257
