BERLIN: Polar bears are starving during their prime hunting period as Arctic ice melts because of climate change, according to a US study published Thursday that analysed the animals’ metabolism for the first time.
Polar bears hunt seals, hence relying on sea ice for their main meal. But as that ice melts, they have to work harder and expend more calories to find their prey, said the study published in the journal Science.
Scientists observed the metabolism of nine female polar bears every spring from 2014 until 2016 in the Beaufort Sea, tracking their size and weight as well as various metabolic indicators from blood and urine samples. They attached GPS collars equipped with video cameras and released them back to the wild for 11 days to study how they forage.
Until then experts had assumed that polar bears required less energy because they have no natural predators and their hunting method does not involve a lot of physical exertion: They sit on ice floes and wait for seals to emerge.
But they found that polar bears need to eat more than 12,000 calories per day, which showed that they have a higher metabolism than was earlier thought. Their energy consumption as calculated during the study was 1.6 times higher than previously thought.
They concluded that a female polar bear must eat a fully grown seal every 12 days to meet its energy requirement. More than half of the bears were decreasing in body mass during their main hunting period, the study found.