Influence of forestry and conspecific attraction on habitat use and reproductive activity of the Canada warbler (Cardellina canadensis) in the western boreal forest: Implications for critical habitat identification

Degree: Master of Science Abstract: Recovery strategies for species at risk are legally mandated in Canada and the Government of Canada must identify which habitat is important for a species and which activities result in its destruction. The Canada Warbler (Cardellina canadensis) has been designated as a threatened species in Canada due to large population declines (~3% annually over the last 50 years). Forestry has been identified as a threat, but some studies suggest it can create productive breeding habitat. I quantified multiple orders of habitat use to study the response of the Canada Warbler to forestry, accounted for the effect of conspecific attraction which may affect habitat use patterns, and assessed how use patterns influenced reproductive activity. Specifically, my first objective was to quantify the relative importance of forestry-related stand metrics versus conspecific proximity on multiple levels of habitat use of Canada Warblers. I used point count surveys and tracked individuals to determine density, 2nd and 3rd order habitat use, and probability of pairing and fledging young for male Canada Warblers in Alberta, Canada. I found fewer territorial males in survey blocks with more harvesting, effects which were not mitigated by retention of unharvested fragments, stand regeneration ≤30 years post-harvest, or abundance of old-growth stands in the surrounding matrix. Male home ranges (2nd order use) in post-harvest were typically near edges of adjacent unharvested stands and near conspecifics. Males also had higher intensity of use in areas within their home ranges (3rd order use) that were further from edges and nearer to conspecifics. This suggests that forest harvesting poses a threat to Canada Warblers in Alberta, and that post-harvest stand use reported in other studies may be influenced more by conspecific attraction than by attributes of post-harvest stands themselves. Hence, large tracts of unharvested stands should be protected in Alberta, with higher prioritization in areas where ...