Short- and Long-Term Influence of Brush Canopy Cover on Northern Bobwhite Demography in Southern Texas

Abstract

Extensive research has been devoted to quantifying the habitat needs and selection of many wildlife species. However, how habitat selection affects the long-term demographic performance of a species largely has been ignored. We used northern bobwhite (Colinus virginianus) and brush canopy coverage—an important habitat component for quail—to evaluate the influence of habitat on short- and long-term demographic performance of this species. We used data from a 5-yr (2001–2005) radiotelemetry study of northern bobwhite in southern Texas to obtain estimates of bobwhite density, survival, and production on three study areas with 5%, 11%, and 32% brush canopy cover. Our objectives were to compare these demographic variables individually among brush canopy cover classes and then simulate their cumulative effect on demographic performance using a simulation model. All demographic parameters were similar among the three brush canopy cover classes. However, simulation modeling indicated that long-term demographic performance was greater on the 11% and 32% brush canopy cover classes. Simulated bobwhite populations were 2–3 times higher in these two cover classes than the 5% brush canopy cover class. In addition, the probability of population persistence was greater in the 11% (0.91) and 32% (1.00) brush canopy cover classes than the 5% cover class (0.54) using a quasi-extinction criterion of ≤ 40 birds (≤ 0.05 birds · ha-1). Our study highlights the shortcoming of considering only short-term effects when comparing habitat given that short- and long-term effects of habitat on demographic performance can differ.