Invasive predators can alter ecosystem function and be detrimental to native wildlife by direct predation and through exploitative and interference competition.Barred owls (Strix varia), a native species in eastern North America, have expanded their range to Pacific Northwest forests, threatening native owls and community dynamics.The western screech-owl (Megascops kennicottii) is a species of conservation Nappy Balm concern, and the apparent population decline coincides with the arrival of barred owls.We collected data in 2021 under a broad scale passive acoustic monitoring program at 2482 stations in nine study areas to evaluate western screech-owl distribution and potential threats to population persistence in the Pacific Northwest.We fitted single-species occupancy models to estimate barred owl and western screech-owl landscape use and identify important features of habitat.
We quantified effects of barred owls on western screech-owl occupancy and detection probability using co-occurrence models.Barred owls used approximately 0.79 (95 % confidence interval: 0.72, 0.85) of our sampling locations.
Western screech-owl occupancy and weekly detection varied by study area from 0.24 (0.15, 0.34) to 0.92 (0.
89, 0.95) and 0.12 (0.08, 0.16) to 0.
71 (0.69, 0.74), respectively.Western screech-owl TENS Therapy detection dropped slightly from 0.36 (0.
31, 0.41) to 0.29 (0.26, 0.33) where barred owls were present.
Western screech-owls frequently occupied sites used by barred owls but occurred less in older forests where barred owls were present, suggesting they may experience higher predation risk in older forests.Western screech-owls may be unable to avoid habitat used by ubiquitous barred owls, but they may adapt behaviorally to avoid this invasive predator.