Do Ovenbirds (Seiurus Aurocapillus) Avoid Boreal Forest Edges? A Spatiotemporal Analysis in an Agricultural Landscape

Abstract

Previous studies suggest that Ovenbirds (Seiurus aurocapillus) are area sensitive and apparently avoid forest edges. In 1999 and 2000, we used radiotelemetry to investigate how breeding male Ovenbirds respond to forest edges. Twenty-one males with home ranges abutting edges of seven forest fragments surrounded by agriculture were tracked for an average of two weeks. We found that sightings of males were situated 8 ± 10 m closer to edges than random locations within each home range. However, the mean time of day for edge sightings (1139 hours, 95% CI = 1052–1227 hours) occurred significantly later than the mean for sightings in the interior of forest fragments (0936 hours, 95% CI = 0856–1016 hours). That indicates that previous studies focusing on morning singing locations to delineate home-range use have likely underestimated use of edges by birds. Habitat characteristics also varied in relation to edges. Forest canopy was lower, shrubs were denser, leaf-litter thicker, and soils dryer near edges than in the portion of home ranges facing the interior of forest fragments. Arthropod biomass varied little in relation to edges, except biomass of larvae, which was greatest at edges. Boreal forest edges abutting agricultural fields do not appear to reduce habitat use or quality for breeding male Ovenbirds, and so we suggest that the generalized association between area sensitivity and edge avoidance for Ovenbirds in forest fragments be reassessed.