Reproductive success of cavity-nesting birds in partially harvested woodlots

Abstract

Cavity-nesting birds are dependent on large declining and dead trees that are frequently removed during partial harvesting. We compared breeding densities, nest survival, nest site characteristics, food abundance, and reproductive parameters of six species of cavity-nesting birds in partially harvested and reference woodlots in southwestern Ontario, Canada. Silvicultural practices significantly altered woodlot structure, with treatment-specific effects on bark arthropod biomass, fledging dates for the Red-bellied Woodpecker ( Melanerpes carolinus (Linnaeus, 1758)), and site suitability for the Yellow-bellied Sapsucker ( Sphyrapicus varius (Linnaeus, 1766)). Red-bellied Woodpecker, Downy Woodpecker ( Picoides pubescens (Linnaeus, 1766)), and Hairy Woodpecker ( Picoides villosus (Linnaeus, 1766)) experienced lower breeding densities in recently cut sites. Daily survival rates were generally greater for nests positioned higher up in large trees and for Northern Flicker ( Colaptes auratus (Linnaeus, 1758)) nests excavated in healthy and hard wood. Conversely, the Black-capped Chickadee ( Poecile atricapillus (Linnaeus, 1766)) had higher daily survival rates in low, small trees (<10 cm diameter at breast height) and sites with lower arthropod abundance. We conclude that although partial harvesting has the potential to decrease cavity-nesting bird breeding densities, conscientious cavity tree retention during harvest may provide suitable nesting sites that maintain high rates of nest success, regardless of the silvicultural treatments that we examined. However, further research is required to monitor these trends beyond a single harvesting rotation.