Does polar bear (Ursus maritimus) foraging on Common eiders (Somateria mollissima) facilitate predation risk from Herring gulls (Larus argentatus)?
Standing
Undergraduate
Type of Proposal
Oral Research Presentation
Faculty
Faculty of Science
Faculty Sponsor
Dr. Christina Semeniuk
Proposal
Due to climate-induced rapid decline in sea-ice, polar bears (Ursus maritimus) are being forced onto land sooner. As a consequence, bears are foraging on Arctic nesting seabird eggs, since their earlier arrival ashore coincides with the seabird’s incubation period. Increasing predation risk by bears may also facilitate traditional egg predators of seabirds. I study predator-prey interactions between Common eiders (Somateria mollissima) nesting on Mitivik Island, Nunavut, Canada (64°0′0″N 81°59′59″W), and their traditional egg predators, Herring gulls (Larus argentatus) during polar bear foraging. Whether polar bear foraging behaviour facilitates gull predation on Common eider eggs via the eiders’ responses to polar-bear risk is currently unknown. Using aerial drone videography, I quantified gull egg-predation success on eider nests during polar bear foraging bouts. I recorded eider behavioural responses following their flush from nests and estimated if these responses influenced the success of gulls predating vacated nests. Preliminary results indicate that 15% of 192 nests vacated by eiders were visited by gulls, suggesting gulls may not be as ubiquitous predators as predicted. However, of the eiders that I observed returning to their nests shortly after flushing, only 10% returned to defend their nest from foraging gulls. Further analysis of results will allow me to determine whether polar bear foraging is facilitating gull predation, thereby causing an increased risk to Common eider reproductive success. Findings can be used in future studies to predict eider persistence as a result of indirect effects of climate change.
Availability
Anytime
Special Considerations
I will be the only presenter
Does polar bear (Ursus maritimus) foraging on Common eiders (Somateria mollissima) facilitate predation risk from Herring gulls (Larus argentatus)?
Due to climate-induced rapid decline in sea-ice, polar bears (Ursus maritimus) are being forced onto land sooner. As a consequence, bears are foraging on Arctic nesting seabird eggs, since their earlier arrival ashore coincides with the seabird’s incubation period. Increasing predation risk by bears may also facilitate traditional egg predators of seabirds. I study predator-prey interactions between Common eiders (Somateria mollissima) nesting on Mitivik Island, Nunavut, Canada (64°0′0″N 81°59′59″W), and their traditional egg predators, Herring gulls (Larus argentatus) during polar bear foraging. Whether polar bear foraging behaviour facilitates gull predation on Common eider eggs via the eiders’ responses to polar-bear risk is currently unknown. Using aerial drone videography, I quantified gull egg-predation success on eider nests during polar bear foraging bouts. I recorded eider behavioural responses following their flush from nests and estimated if these responses influenced the success of gulls predating vacated nests. Preliminary results indicate that 15% of 192 nests vacated by eiders were visited by gulls, suggesting gulls may not be as ubiquitous predators as predicted. However, of the eiders that I observed returning to their nests shortly after flushing, only 10% returned to defend their nest from foraging gulls. Further analysis of results will allow me to determine whether polar bear foraging is facilitating gull predation, thereby causing an increased risk to Common eider reproductive success. Findings can be used in future studies to predict eider persistence as a result of indirect effects of climate change.