California's Sierra Nevada is on the brink of transformation, and ecological changes are increasingly manifested at broad spatial scales. The California spotted owl (Strix occidentalis occidentalis) is threatened by at least three of the "big four" threats to biodiversity: habitat loss, invasive species, and climate change. Conserving the spotted owl will therefore require multifaceted responses implemented at scales commensurate to those threats. Because so much is already known about the spotted owl's natural history, it can also serve as a model species for the development of conservation techniques. Historically, spotted owls were studied with mark-recapture techniques, which yield detailed data but cannot be implemented at landscape scales. The core of my dissertation entailed the development of a landscape-scale acoustic monitoring program. To my knowledge it is one of the biggest such studies in the western hemisphere.Chapter 1 draws on conventionally collected data to address the challenge of balancing spotted owl habitat preservation with fuel reduction treatments to restore ecosystem resiliency. The other three chapters build off the implementation acoustic surveys across the northern third of the Sierra Nevada and the development of bioacoustic tools to extract spotted owl and barred owl (S. varia) vocalizations from the resulting data. Chapter 2 documented a 2.6-fold increase in barred owl site occupancy in that region in a single year, indicating that prompt action is needed to manage this invasive competitor. Chapter 3 drew on that acoustic data, GPS-tag data, stable isotopes, and phenotypic data to show that niche overlap and hybridization between spotted and barred owls are density dependent. In Chapter 4 I developed and demonstrated three novel methods of enriching acoustic monitoring data collected in an occupancy framework, including a reliable means of differentiating individuals.