Canada Warbler (Cardellina canadensis) response to vegetation structure on regenerating seismic lines

  • Author / Creator
    Gregoire, Jocelyn M.
  • Seismic lines have an extensive footprint in Canada’s western boreal forest and cause habitat removal, degradation, and fragmentation. Changes in practices and regulations for operations and reclamation have led to an accumulation of legacy seismic lines that exist within a range of seral states. Forest regeneration is often hindered on seismic lines as they are frequently repurposed for recreational or alternative industrial uses. This has implications for migratory songbirds for which the boreal forest is an important source of breeding habitat. The Canada Warbler is one such species which has a widespread, but sporadic distribution across Canada’s boreal region during the breeding season. It has been identified as a species at risk both federally (Threatened) and provincially within Alberta (Sensitive). The responses of Canada Warbler to seismic lines has been a significant gap in our understanding of this species locally.
    The goal of this project was to address these knowledge gaps and to determine whether regeneration of vegetation on seismic lines has influenced Canada Warbler responses. To explore these questions, I used playback surveys along seismic lines within Canada Warbler habitat to identify locations of Canada Warbler territories. Grids of autonomous recording units were then deployed on these lines and acoustic source localization (ASL) was conducted to precisely map spatial locations of territorial singing events. Canada Warblers were only found to avoid seismic lines with little to no woody vegetation based on ordinal categories of overall regeneration and were more actively engaged in territorial behaviour with increased shrub cover on the line. Birds used the seismic line and its edge, but did not select for the line when compared to availability. Given these results and the fact that most lines have some level of woody regeneration cover, the effects on Canada Warbler populations are not likely to be large. However, even the most overgrown seismic lines were still a feature and influenced their use of space. To mitigate the local scale effects of seismic lines to Canada Warblers, a more inclusive approach to seismic line restoration is required which accounts for unique habitats and promotes regeneration to the pre-existing state. This will also reduce the potential for any population level consequences that may occur with climate change and the reduction in suitable habitat.

  • Subjects / Keywords
  • Graduation date
    Fall 2021
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.