Polar bears are inefficient predators of seabird eggs ...

• Main Author: Jagielski, Patrick
• Format: Dataset
• Language: English
• Published: Dryad 2020
• Subjects: Canada; Nunavut; Common Eider; Sea ice; Somateria mollissima; Ursus maritimus
• Online Access: https://dx.doi.org/10.5061/dryad.prr4xgxjw; https://datadryad.org/stash/dataset/doi:10.5061/dryad.prr4xgxjw

Climate-mediated sea-ice loss is disrupting the foraging ecology of polar bears (Ursus maritimus) across much of their range. As a result, there have been increased reports of polar bears foraging on seabird eggs across parts of their range. Given that polar bears have evolved to hunt seals on ice, they may not be efficient predators of seabird eggs. We investigated bears’ foraging performance on common eider (Somateria mollissima) eggs on Mitivik Island, Nunavut, Canada to test whether bear decision-making heuristics are consistent with expectations of optimal foraging theory. Using aerial-drones, we recorded multiple foraging bouts over eleven days, and found that as clutches were depleted to completion, bears did not exhibit foraging behaviours matched to resource density. Bears visited fewer nests overall as the season progressed, but marginally increased their visitation to nests that were already empty. Bears did not display different movement modes related to nest density, but became less selective in ... : Polar bear observations We recorded foraging bears with drones (DJI Phantom 3 Pro and 4 Pro models, www.dji.com) from July 10-20, 2017 between 0530 hrs and 2030 hrs. We initiated filming when conditions were suitable for flying and when bears were actively foraging on eggs. Bears were filmed as soon as researchers noticed them on the island and bears were recorded until they either left the island or were resting for extended periods of time. The drone pilot and observer were stationed on the roof of a research cabin and launched/landed the drone within an electrified fence surrounding the research station. Drones were flown above the focal bear at altitudes that elicited minimal apparent behavioural responses (we suspect that any minimal behavioural response was also due to ambient noise of the colony, and bears continually being harassed by herring gulls (Larus argentatus); Figure 2a), although we cannot say with absolute certainty that bears and eiders were not affected physiologically (i.e., changes in ...