Nest predation on forest songbirds in a western boreal forest landscape altered by energy sector linear features

  • Author / Creator
    Ball, Jeffrey R
  • Nest predation is a major source of reproductive failure for many species of songbirds. Habitat fragmentation by human land use creates edge habitat that can alter predator-prey dynamics, create ecological traps, and reduce the amount of high quality habitat available for sustaining bird populations. I studied the nesting success of boreal forest songbirds in two regions of western Canada fragmented by pipelines, seismic lines, and service roads. These linear features result in relatively little forest loss but create vast amounts of edge. Our ability to predict the effect of these edges is hampered by incomplete or inaccurate knowledge about what predators depredate nests and how those predators respond to edges. My objective was to determine if edges were negatively impacting songbird nest success through increased rates of nest predation and whether birds were preferentially using habitats with higher reproductive potential. Using video monitoring, I identified 11 species of nest predators at 71 songbird nests. Red squirrels were the dominant nest predator in both regions and all predators were endemic boreal species rather than non-forest species. I did not find strong evidence that the spatial distribution or probability of nest predation by the majority of nest predators was strongly affected by edge proximity. Of all the predators monitored, only bears and deer mice were more common near edges but they depredated few nests. I also did not find strong support for a negative edge effect of linear features on songbird nest fate (n = 571 nests) relative to forest interiors. Ground nest survival was marginally higher near edges and ground and shrub nest survival was marginally higher where squirrels were absent. In contrast, the survival of canopy nests was higher away from the edge and in the presence of squirrels. Abundance of singing males and nest fate of each guild responded similarly to edges and squirrels indicating birds are preferentially using habitats with higher reproductive potential. Uncertainties in field-based estimates of nesting success and other important demographic parameters prevent me from concluding that higher quality habitats are capable of sustaining the local population.

  • Subjects / Keywords
  • Graduation date
  • Type of Item
  • Degree
    Doctor of Philosophy
  • 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.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
    • Department of Biological Sciences
  • Specialization
    • Ecology
  • Supervisor / co-supervisor and their department(s)
    • Bayne, Erin (Biological Sciences)
  • Examining committee members and their departments
    • St. Clair, Colleen (Biological Sciences)
    • Boutin, Stan (Biological Sciences)
    • Boyce, Mark (Biological Sciences)
    • Nol, Erica (Biology Department)