Effects of Southern Flying Squirrels on Nest Success of Red-Cockaded Woodpeckers

Abstract

Recovery efforts for endangered red-cockaded woodpeckers (Picoides borealis) often include control of southern flying squirrels (Glaucomys volans). Nevertheless, few studies demonstrate directly that this control improves nest success of red-cockaded woodpeckers. and no experimental studies have evaluated what form of flying squirrel management is most effective. Therefore, in 1996 and 1997 at Fort Stewart, Georgia, we quantified the nesting suecess of red-cockaded woodpeckers in 30 cavity-tree clusters from which flying squirrels were removed. 30 clusters in which flying squirrels were excluded from cavities with squirrel-excluder devices. and 30 control clusters with no flying squirrel management. Removal or exelusion of flying squirrels did not affect the likelihood that red-cockaded woodpeckers would initiate a nest or the median date the first egg was laid in either year. In 1996 (but not 1997), red-cockaded woodpeckers were more likely to nest successfully (produce >1 fledgling) in clusters from which flying squirrels were removed. However, in both years of our study, nests in flying squirrel removal clusters were more likely to experience partial nest loss (disappearance of a portion of their eggs or nestlings). As a net result. the number of eggs, nestlings. and fledglings did not differ among treatments in 1996 or 1997. Removal or exclusion of flying squirrels did not increase the percentage of clusters fledging young or the number of young fledged per cluster. We sugges routine control of flying squirrels is not necded in healthy populations of red-cockaded woodpeckers.