Winter avian use of fragmented woodlands.

Abstract

Winter birds inhabiting small fragmented woodlands were studied in three riparian areas near Emporia, Lyon County, Kansas. Study areas varied in size and shape, but all were dominated by hackberry (Celtis occidentalis) and were not significantly different in regard to overall vegetation structure or composition. Two study areas, of 4.0 ha and 8.3 ha, were roughly triangular in shape. The third study area (3.7 ha) was a linear-shaped woodlot that had a much higher edge ratio. The purpose of this research was to determine if size and shape of fragmented woodlands were important factors affecting wintering bird species richness, diversity, and density. A total of 43 bird censuses was conducted in each study area during the winters of 1980-81 and 1981-82. Bird species richness, diversity, and density were calculated for each census, and statistical comparisons were made among the three study areas. Results demonstrated that size and shape of forest fragments are important variables that affect winter avian use. The larger study area had significantly greater bird species richness, diversity, and densities. Comparisons of the two smaller study areas revealed that the study area with the lower edge ratio had signi£icantly greater bird species richness and density. Increased species richness was the result o£ the addition o£ both permanent-resident and migratory winter-resident bird species. When considered in combination with the £indings o£ numerous breeding bird studies, these results suggest that permanent-resident woodland birds may be more selective of their habitat in winter than during the breeding season.