Nest tree use by primary cavity-nesting birds in south central British Columbia

Abstract

Heartwood decay was the most important factor in nest tree selection by primary cavity-nesting birds in the Interior Douglas-fir Biogeoclimatic Zone of British Columbia. Of 243 active nests, most were in trembling aspen (Populus tremuloides) and paper birch (Betula papyrifera). Douglas-fir (Pseudotsuga menziesii) and hybrid spruce (Picea engelmannii × glauca) were not used for nesting. Strong excavators (Yellow-bellied Sapsucker (Sphyrapicus varius), Pileated Woodpecker (Dryocopus pileatus), and Hairy Woodpecker (Picoides villosus)) preferred to nest in live trembling aspen with heartwood decay. Weak excavators (Red-breasted Nuthatch (Sitta canadensis), Northern Flicker (Colaptes auratus), and Downy Woodpecker (Picoides pubescens)) preferred to nest in dead trees or dead tops of live trees. Yellow-bellied Sapsucker preferred to nest in trees larger than 30 cm diameter at breast height, and Pileated Woodpecker preferred trees larger than 40 cm diameter at breast height. No significant preference for nest tree diameter was detected for other species.