Evaluating Micro-habitat Selection by Northern Bobwhite in Virginia

We monitored radio-tagged northern bobwhites (Colinus virginianus) from January through July of 1990 and 1991 to determine if preferential habitat use occurred within the covey home range. We generated estimates of percent bare ground, average height of herbaceous vegetation, percent canopy cover of herbaceous vegetation and honeysuckle (Lonicera spp.), proportion of the herbaceous canopy represented by grasses, herbaceous quail foods, and woody vegetation <2 m tall at used and unused sites within 12 covey home ranges. We pooled the data within each home range and used 2 approaches to evaluate the extent to which these 7 variables influenced habitat use. First, we compared means from used and unused sites for each of the 7 parameters with a Wilcoxon signed-rank test. Additionally, we regressed means from used sites on estimates from unused sites. The 2 approaches used to evaluate habitat selection yielded different results. Whereas the signed-rank test yielded significant (P = 0.04) results for only herbaceous quail foods (sites with higher cover of food were selected), results from the regressions were all significant (P < 0.05), indicating disproportional use of habitat characteristics except for cover of woody vegetation <2 m tall. Finally, we used data from use-sites to construct Suitability Index (SI) curves for bare ground, herbaceous quail foods, and woody vegetation <2 m tall. Our SI curves for bare ground and herbaceous quail foods were similar to the curves in the HSI model (Schroeder 1985). Our findings suggest that proportion of herbaceous canopy that is grass, total herbaceous cover, honeysuckle, herbaceous quail foods, and most especially bare ground, likely influence habitat use within the covey home range.

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