The influence of habitat disturbances on bird populations

The influences of timber removal, wildlife clearings, and forest cover types on bird populations in southwestern Virginia were evaluated. Timber was cut two to six years prior to the study. The oak, hickory, poplar, and white pine; and mixed oak cover types were found on bottom slope sites. Mixed oak-pine and mixed oak occurred on middle slope sites. Forests were in the pole stage of development. Two trails traversed mixed oak, pine-bear oak, cove hardwood, chestnut oak, and oak-hickory forest cover types. Wildlife clearings seeded to bluegrass and clover were 0.9 to 108 acres in size.

Four transects, 200 ft X 1,000 ft, were located in each of the following habitats: cut and uncut, bottom and middle slope stands. Three transects were located in cut and three in uncut middle slope stands with wildlife clearings. Twenty transects were located along the trails.

Significantly more birds inhabited cut stands during the breeding and late summer periods; and significantly more birds inhabited uncut stands during the winter. Bird usage was equal in the fall. Wildlife clearings had no detectable effect on bird density.

On the trails, burned and cut forest stands had the highest bird densities during the breeding and late summer periods. Of the undisturbed forest cover types, the cove hardwoods had the highest density for all seasons but the winter.

In uncut forest stands, breeding bird density was directly correlated with understory development. A suggested management practice is to open the crown closure to increase understory density.