The Effects of Landscape Characteristics on Northern Bobwhite Density

• Published in: The Journal of wildlife management 2021-07, Vol.85 (5), p.1001-1008
• Main Authors: HOWELL, PAIGE E., WILHITE, NATHAN G., GARDNER, RACHEL, MOHLMAN, JESSICA L., CHANDLER, RICHARD B., PARNELL, IRA B., MARTIN, JAMES A.
• Format: Article
• Language: English
• Subjects: Age composition; Birds; Canopies; Capture-recapture studies; Colinus virginianus; Data collection; Density; Di‐Lane; Georgia; Habitat Relations; Hardwoods; Modelling; monitoring; Nesting; northern bobwhite; Population; Population density; Population number; Population statistics; Population structure; Population viability; spatial capture‐recapture; Spatial variations; Telemetry; Wildlife management
• ISSN: 0022-541X; 1937-2817
• DOI: 10.1002/jwmg.22057

The northern bobwhite (Colinus virginianus) is an ecologically and economically valuable species in the United States. Managers rely on autumn density estimates to set harvest regulations, balancing the interests of hunters and long-term bobwhite population viability. Spatial capture-recapture (SCR) is a useful framework for estimating population size and modeling spatial variation in density. We used SCR to quantify the effect of landscape structure on spatial variation in density for a population of bobwhites on the Di-Lane Wildlife Management Area in Waynesboro, Georgia, USA. Without additional telemetry or nesting data, we were also able to estimate a spatially explicit metric of productivity. To sample the population, we deployed a fixed array of 395, 262, and 268 funnel traps in 2016, 2017, and 2018, respectively. We estimated age structure, with the highest density of juveniles (0.32 birds/ha, 95% CI=0.28–0.37) and adults (0.10 birds/ha, 95% CI=0.08–0.12) estimated in 2016. In our top model, density was negatively related to the proportion of closed canopy hardwoods. To increase bobwhite density on the landscape, managers should reduce the amount of closed canopy hardwood forest. Furthermore, the spatially explicit age ratio we estimated could be used to target management towards increasing the recruitment of chicks into the autumn population. An SCR approach may require additional logistical and financial resources relative to other data collection methods, but it makes modeling spatial variation in density straightforward and can be used to gather data to simultaneously understand population structure, vital rates, and movement.