Polar bear energetic and behavioral strategies on land with implications for surviving the ice-free period

Nature Communications
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Abstract

Declining Arctic sea ice is increasing polar bear land use. Polar bears on land are thought to minimize activity to conserve energy. Here, we measure the daily energy expenditure (DEE), diet, behavior, movement, and body composition changes of 20 different polar bears on land over 19–23 days from August to September (2019–2022) in Manitoba, Canada. Polar bears on land exhibited a 5.2-fold range in DEE and 19-fold range in activity, from hibernation-like DEEs to levels approaching active bears on the sea ice, including three individuals that made energetically demanding swims totaling 54–175 km. Bears consumed berries, vegetation, birds, bones, antlers, seal, and beluga. Beyond compensating for elevated DEE, there was little benefit from terrestrial foraging toward prolonging the predicted time to starvation, as 19 of 20 bears lost mass (0.4–1.7 kg•day−1). Although polar bears on land exhibit remarkable behavioral plasticity, our findings reinforce the risk of starvation, particularly in subadults, with forecasted increases in the onshore period.

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Publication type Article
Publication Subtype Journal Article
Title Polar bear energetic and behavioral strategies on land with implications for surviving the ice-free period
Series title Nature Communications
DOI 10.1038/s41467-023-44682-1
Volume 15
Publication Date February 13, 2024
Year Published 2024
Language English
Publisher Nature
Contributing office(s) Alaska Science Center Ecosystems
Description 947, 15 p.
Country Canada
State Manitoba
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