WEYDV-02-055

Effects of Partial-Cutting on Migratory Songbirds Breeding in Alberta's Boreal Mixed-Wood Forest
Sponsor: 
Weyerhaeuser Company Limited
Lead Researcher: 
Rebecca Tittler, Masters student, University of Alberta, Edmonton
Body: 
This project is a continuation of a short-term project that studied the effects of partial-cutting on migratory breeding songbirds in Weyerhaeuser’s Slave Lake Forest Management Agreement (FMA) area between 1994 and 1995. Research from the original study focused on the first year after harvest. As a continuation, the new study looks at the effects of partial-cutting on bird species richness and abundance three years after harvest. The researcher examines the influence of varying levels of residual tree retention on forest and open-area songbird abundances, and the effects of residual tree retention on nest predation in and adjacent to harvested sites.

Birds were censused at 12 sites in 1994 and 1995 and at 18 sites in 1997. In the winter of 1994-95, 9 of the 12 and 12 of the 18 sites were logged while the remaining sites were left forested and served as a control. All sites were aspen-dominated, mixed-wood stands greater than 130 years old prior to harvest. The sites were between 10 and 35 ha in size with residual densities ranging from 10 to 133 trees/ha.

Forest songbirds were found to be more abundant in forested sites as opposed to logged sites in the two years following harvest. There were few differences among forest species between sites with varying densities of residual trees, and nest predation did not differ among sites or stands adjacent to sites with varying densities of residual trees. In the third year post-logging, the majority of forest songbirds were found to not be affected by the density of residual trees within the range measured.