Tree cover limits occupancy of a declining game bird

Open forest ecosystems are considered one of the most imperiled ecosystems in North America and many associated avian species are experiencing population declines. Management at large and impactful scales is challenging on private lands due to fragmentation and resource limitations, but public lands are often larger in scale and offer opportunities for landscape level conservation of species of conservation concern. Northern bobwhite (Colinus virginianus; bobwhite) is a popular but declining game bird which is often considered an umbrella and indicator species for savanna ecosystems. To evaluate the effects of tree canopy cover and prescribed fire frequency (1 Jan 2010 – 15 May 2024) on bobwhite occupancy we surveyed 144 sites 11 times during 15 May – 17 June 2024 using acoustic recording units on the Sabine and Angelina National Forests of Texas. Probability of bobwhite occupancy decreased as canopy cover increased (βTree = -0.74, 95% CrI: -1.29 – -0.28); occupancy was over 19 times higher when canopy cover was 44% versus the mean observed value of 80.8% (range: 38–96%). Despite a well-established positive relationship of bobwhite and prescribed fire based on previous research, we found tree canopy obfuscated any effects of fire frequency on bobwhite occupancy (βFire = -0.09, 95% CrI: -0.57 – 0.43). Only 2 of 144 sites were characterized by low-moderate canopy cover (<50%) with a moderate fire frequency (burned 5 and 7 times since 2010). Our results underscore the importance of forest thinning in addition to prescribed fire for managing species which require savanna conditions.