Data on nocturnal owls are often insufficient for making broad-scale assessments of population status or setting local conservation targets. To achieve these objectives, targeted surveys combined with modern analytical techniques are required. Using data from a 15-yr (2008–2023) nocturnal owl survey, we assessed route-level, regional, and provincial relative abundance trends for Barred Owl (Strix varia), Boreal Owl (Aegolius funereus), Northern Saw-whet Owl (Aegolius acadicus), and Great Horned Owl (Bubo virginianus) in the southern portion of Québec using continuous- and discrete-space spatially explicit modeling approaches. Results from this study reflect spatial patterns in owl trends at finer scales than previously reported. For example, significantly negative route-level trends were detected once for Great Horned Owl (of 21; 5%) and across 20 routes for Northern Saw-whet Owl (of 25; 80%). Great Horned Owl and Northern Saw-whet Owl had significant negative regional trends in nine (of 33; 26%) and 23 (of 34; 70%) 100 × 100-km grid cells, respectively. However, posterior median values for the temporal trend across the study area suggest some evidence that Northern Saw-whet Owl (annual change: −4.23%; credible interval [CI]: −9.30 to 3.05) and Great Horned Owl (−3.76%; CI: −13.36 to 7.89) populations were in decline, and Barred Owl (1.16%; CI: −2.18 to 5.63) and Boreal Owl (2.92%; CI: −14.05 to 28.00) populations were increasing, although none of these trends was significant. The increased spatial resolution of trends may help researchers and managers test hypotheses of drivers of change to facilitate the development of locally tailored conservation plans.

© 2025 The Raptor Research Foundation, Inc.
2025
You do not currently have access to this content.