Polar bears could be sliding towards extinction faster than previously feared, with the animals facing an increasing struggle to find enough food to survive as climate change steadily transforms their environment.
New research has unearthed fresh insights into polar bear habits, revealing that the Arctic predators have far higher metabolisms than previously thought. This means they need more prey, primarily seals, to meet their energy demands at a time when receding sea ice is making hunting increasingly difficult for the animals.
A study of nine polar bears over a three-year period by the US Geological Survey and UC Santa Cruz found that the animals require at least one adult, or three juvenile, ringed seals every 10 days to sustain them. Five of the nine bears were unable to achieve this during the research, resulting in plummeting body weight – as much as 20kg during a 10-day study period.
“We were surprised to see such big changes in body masses, at a time when they should be putting on bulk to sustain them during the year. This and other studies suggest that polar bears aren’t able to meet their bodily demands like they once were.”
Pagano’s team studied the bears in a period during April over the course of three years, from 2014 to 2016, in the Beaufort Sea off Alaska. They fitted the bears with GPS collars with video cameras to measure activity levels. Blood chemistry was also taken from the bears.
Previously, polar bears were thought to expend relatively little energy during days where they often wait for hours beside holes in the ice, which seals emerge from in order to breathe. But the researchers found that they actually have an average metabolism 50% higher than prior estimates.
With previous studies showing recent drops in polar bear numbers, survival rates and body condition, scientists said the new research suggests the species is facing an even worse predicament than was feared.
The Arctic is warming twice as rapidly as the global average, diminishing the sea ice that polar bears rely upon for food and forcing many to embark from water on to land where they desperately forage for goose eggs or rubbish from bins in far-flung towns.