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Conservation Science for a Healthy Planet

Polar bears finding it harder to catch enough seals to meet energy demands

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February 1, 2018  University of California – Santa Cruz read full ScienceDaily article here
A new study finds polar bears in the wild have higher metabolic rates than previously thought, and as climate change alters their environment a growing number of bears are unable to catch enough prey to meet their energy needs.
…”We’ve been documenting declines in polar bear survival rates, body condition, and population numbers over the past decade,” said Anthony Pagano, a Ph.D. candidate at UC Santa Cruz.. “This study identifies the mechanisms that are driving those declines by looking at the actual energy needs of polar bears and how often they’re able to catch seals.”…

….Climate change is having dramatic effects on the Arctic sea ice, forcing polar bears to move greater distances and making it harder for them to catch prey. In the Beaufort Sea, sea ice starts to retreat away from the continental shelf in July, and most of the bears move north on the ice as it retreats. As the Arctic warms and more sea ice melts, the bears are having to move much greater distances than previously. This causes them to expend more energy during the summer, when they are fasting until the ice returns to the continental shelf in the fall.

In other areas, such as Hudson Bay, most bears move onto land when the sea ice retreats. There, Arctic warming means the sea ice is breaking up earlier in the summer and returning later in the fall, forcing bears to spend more time on land.

This is an adult female polar bear on the sea ice wearing a GPS satellite video-camera collar. GPS video-camera collars were applied to solitary adult female polar bears for 8 to 12 days in April, 2014-2016. These collars enabled researchers to understand the movements, behaviors, and foraging success of polar bears on the sea ice. Credit: Anthony Pagano, USGS
A. M. Pagano, G. M. Durner, K. D. Rode, T. C. Atwood, S. N. Atkinson, E. Peacock, D. P. Costa, M. A. Owen, T. M. Williams. High-energy, high-fat lifestyle challenges an Arctic apex predator, the polar bear. Science, 2018; 359 (6375): 568 DOI: 10.1126/science.aan8677

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