Life on a knife edge:
The metabolic demands
facing polar bears.
Polar bears rely on marine mammals such as seals which are high-fat prey. Despite the richness of their diet however, new research suggests that a reduction in the prey availability can have severe consequences on polar bear survival.
Pagano et al (2018) monitored nine free-ranging female polar bears over 2 years, measuring their metabolic rates, daily activity patterns, body condition and foraging success. They found that more than half of the bears had an energy deficit resulting from a high metabolic rate (1.6 times higher than previously assumed) and a low intake of the high-fat prey. As fragmentation of sea ice continues and seals become harder to catch the high metabolic requirements of polar bears is likely to become increasingly catastrophic for the species.
Original research: https://doi.org/10.1126/science.aan8677