Effects of Microhabitat on Nest Box Selection and Annual Productivity of Eastern Bluebirds (Sialia Sialis) in Southeastern Georgia‪.‬

ABSTRACT. -- We assessed the effects of 15 microhabitat variables (that is, habitat variables measured within a 10-meter radius of the nest box) on artificial nest site selection and on annual productivity (total number of eggs per nest per year = TOTEGGS) of eastern bluebirds (Sialia sialis) in southern Georgia. Sixty-nine (1990) and 74 (1991) artificial nesting boxes were monitored near Statesboro, Georgia, from March through July during both years of the project. A Multivariate Analysis of Variance (MANOVA) was used to compare the raw microhabitat variables surrounding selected boxes as opposed to unselected boxes. In both years of the study, microhabitat surrounding selected and unselected boxes did not differ significantly. The raw variables surrounding boxes that were occupied were further recombined using Principal Components Analysis (PCA). Annual productivity (TOTEGGS) was regressed against the resulting first six principal component scores. During the 1990 breeding season, TOTEGGS was significantly correlated with PRIN1 (openness) and PRIN4 (orientation of nest box). In 1991 however, none of the first six principal components were significantly correlated with TOTEGGS.