If you’ve ever wanted to experience a day in the life of a polar bear, you’re in luck.
Cameras were fastened to a bunch of bears to see exactly what they were getting up to during an Arctic summer.
The research revealed the bears were forced to spend more time on land due to rapidly shrinking sea ice, where they are less adapted to hunt and forage for food.
One video shows a polar bear chewing on some antlers. Another is seen grazing for berries.
Over three weeks, the bears lost 1kg a day on average.
The findings highlight the increased risk of starvation polar bears face as climate change increases the length of the ice-free Arctic summer.
The study, led by researchers from Washington State University and US Geological Survey (USGS), monitored 20 polar bears in the western Hudson Bay region of Canada, onshore over several weeks in August to September between 2019 and 2022.
Hudson Bay has seen the ice-free period increase by three weeks from 1975 to 2015, reducing the amount of time polar bears can spend on the ice, where they catch and eat seals to bolster their energy reserves.
The bears now spend around 130 days on land near Hudson Bay, up from 100 to 110 days previously.
At the start of each study period the bears were weighed, assessed, and fitted with GPS tags and cameras. They were weighed again at the end of the three week period.
The study revealed they have a wide range of strategies on land, from hibernation-like resting to conserve energy, to actively foraging for food on land.
Bears consumed berries, vegetation, birds, bones and antlers, but there was very little benefit from foraging, as 19 of the 20 animals lost weight during the period.
Only one increased its weight, after likely finding a marine mammal such as a seal or beluga carcass on land, the researchers said.
Two female bears were predicted to starve to death before the average November 30 freeze-up of the Hudson Bay, the study found.
Lead author Anthony Pagano, research wildlife biologist at the USGS, said: ‘We found a real diversity of bear behaviours, and as a result, we saw a diverse range of energy expenditures.
‘The terrestrial foods did give them some [energy], but ultimately, the bears had to spend more energy to access those resources.
‘As polar bears are forced on land earlier, it cuts into the period that they normally acquire the majority of the energy they need to survive.
‘With increased land use, the expectation is that we’ll likely see increases in starvation, particularly with adolescents and females with cubs.’
He added: ‘Our results suggest that polar bears cannot alter their behaviour or energetics in ways that can prevent weight loss when summering on land and that, in most cases, the resources available on land are insufficient to counteract weight loss.’
This means suggestions the Arctic’s top predators could act like their grizzly bear cousins by resting or foraging for food on land are unlikely to work.
Charles Robbins, director of the Washington State University Bear Centre and co-author of the study, said neither strategy of resting to conserve energy or foraging would allow polar bears to exist on land beyond a certain amount of time.
Even those bears that were foraging lost body weight at the same rate as those that laid down.
‘Polar bears are not grizzly bears wearing white coats. They’re very, very different,’ he said.
[Source: Metro UK]
