Cavity Number and Use by Other Species as Correlates of Group Size in Red-Cockaded Woodpeckers

Abstract

I examined cavity number and use by other species as correlates of Red-cockaded Woodpecker (Picoides borealis) group size at Camp Blanding Training Site (CBTS) and Goethe State Forest (GSF), Florida. Group size was positively correlated with cavity number at CBTS but not at GSF. Other species occupied 1.75 (34%) and 1.19 (27%) cavities/territory at CBTS and GSF, respectively. Statistically controlling for use by other species yielded significant positive correlations between group size and cavity number in 4 of 5 years at CBTS and 2 of 4 years at GSF. Correlations between group size and total use by other species, controlling cavity number, were significantly negative at both sites. Separating total use by species, group size was negatively correlated only with southern flying squirrels (Glaucomys volans) at CBTS and only with Red-bellied Woodpeckers (Melanerpes carolinus) at GSF, as flying squirrels occupied >3 times more cavities/territory at CBTS than at GSF (0.87 vs. 0.28) while Red-bellied Woodpeckers occupied ∼0.75 cavities/territory at both sites. Flying squirrels may obscure the relationship between the two woodpecker species by limiting their cavity use.