Demography and Conservation of California Spotted Owls


In close collaboration with Dr. R.J. Gutiérrez (University of Minnesota), our research group studied the demography of California spotted owls in central Sierra Nevada from 1986 through 2021. Our primary goals were to monitor the status of owls in the central Sierra, and to try to understand the environmental factors and forest management practices that impacted owl population dynamics. In conjunction with the basic demographic study, we conducted many other related ecological studies of the California spotted owl regarding habitat use, life-history strategy, genetics and phylogeny, stress physiology, climactic variation, acute responses to canopy reduction, the effectiveness of spotted owl management strategies, and the effects of other owl species on spotted owl response rates during surveys. Ultimately, these results were translated into recommendations to land management agencies such as the US Forest Service who are responsible for maintaining viable owl populations.

We continue to draw upon data from this important long-term study to answer basic questions about California spotted owl biology and to inform spotted owl management into the future. Below we highlight and link to some of the major papers from our lab that resulted from the California Spotted Owl Demography project.

Sierra Nevada Adaptive Management Project

In collaboration with the University of California-Berkeley and the University of Minnesota, we conducted basic science and management driven experiments as part of the Sierra Nevada Adaptive Management Project (SNAMP) from 2007 through 2013. This project was an integrated effort consisting of several teams which together, used landscape-scale experiments designed to test the effects of proposed forest fuel reduction treatments called Strategically Placed Landscape Area Treatments, (SPLATs), on forest health, fire behavior, water resources, and wildlife.

The owl team investigated whether the long-term benefits of reduced fire risk due to SPLAT implementation outweighed any short-term impacts on owl habitat. The orange polygon in the figure to the right represents an area within an owl territory (green circle) that was treated with a SPLAT. To assess short- versus long-term tradeoffs of SPLATS to owls, we measured the effects of SPLATs on owl survival, occupancy, and reproductive rates and using resultant relationships to parameterize a spatially-explicit population viability analysis that predicted how altered fire regimes might benefit owl populations.

The results generated from this project continues to inform California spotted owl management into the future. Please use the links below to see a few of the major papers from our lab that resulted from the Sierra Nevada Adaptive Management Project.