Indirect effects of conifer release alternatives on songbird populations in northwestern Ontario

Abstract

The effects of conifer-release alternatives on songbird densities (determined by territory mapping, mist netting, and handing) in four young (four to seven year old) spruce plantations were examined. Twenty to 38 (block dependent) species bred on each treatment block. Post-treatment data revealed no major treatment-related changes in breeding bird species composition. The mean density of all birds decreased from 6,9 pairs ha-1 pre-treatment, to 6.3 pairs h-1 in the first post-treatment growing season (P > 0.05). Mean densities of the 11 most common species increased by 0.35 h-1 on the control plots during the first post-treatment growing season, but decreased on treated plots by 1.1 h-1 (brush saw), 1.6 h-1 (Silvana Selective), 0.14 ha-1 (Release®) and 0.72 h-1 (Vision®). Following the conifer-release treatments, Chestnut-sided Warbler (Dendroica pensylvanica) had lower (P < 0.05) mean densities on the brush saw- and Silvana Selective-treated plots than on the control plots and fewer (P < 0.05) female birds were captured in the first post-treatment year.