He Arctic is rapidly losing sea ice due to the climate crisis and is expected to disappear completely by the summer of 2030. Given this situation, an international research team, led by the Alaska Science Centerhas studied how animals behave polar bears (Sea bear) before this thaw.
To do this, they used chains with video cameras and GPS follow 20 polar bears during the summer season Arctic —August to September — between 2019 and 2022 in western Hudson Bay, Canada. The region’s ice-free period increased by three weeks between 1979 and 2015, keeping bears on land for about 130 days over the past decade.
The authors checked their daily energy consumptionThe changes in body mass, diet, behavior and movement. Their goal was to find out what these ice top predators ate and did during the long periods of time they spent on land when their favorite prey, seals, were out of reach.
“We were able to document their behavior, weight change, energy costs and movements, allowing us to determine that the bears exhibited a variety of behaviors and energy strategies during the summer on land, but that these did not prevent weight loss. 19 out of 20 polar bears lost body mass in our study,” says Karyn Roderesearcher of Alaska Science Center and co-author of the study published in the journal Nature communication.
Among these tactics to spend less energy are: fasting, exercising less and eating berries and birds. All were performed regardless of age, sex, reproductive stage (pregnant females were also monitored) or initial fat levels. However, they were unable to avoid losing an average of one kilogram per day. Even those who foraged lost weight at the same rate as those who lay down. Only one of them arrived after coming across a dead marine mammal.
“Our results support previous studies indicating that when polar bears longer periods pass summer in the countrythey lose more and more weight the longer it takes,” the researcher emphasizes.
Support polar bear conservation efforts
As sea ice continues to retreat, we need to understand it adaptive behavior is fundamental to conservation efforts aimed at supporting nature polar bears in a rapidly changing ecosystem.
Between late spring and early summer, polar bears use sea ice as a platform seal hunting especially during parturition and weaning of their young.
There are some populations – out of 19 recognized in the entire world Arctic circumpolar – which have access to the carcasses of marine mammals, such as whales, while on land, which would help them compensate for weight loss. But in Hudson Bay, bears currently do not have these types of marine resources on land and are likely to be negatively affected by extended ice-free periods.
“Environment and Climate Change Canada has maintained a long-term research program, which allowed us to closely monitor these animals for approximately three weeks while they were on land,” the scientist explains.
Anthony Paganonature expert in the research program Polar bears of the US Geological Survey notes that “rich foods provided them with some energetic benefit, but ultimately they had to expend more energy to access those resources.”
The research required collaboration between multiple organizations and agencies across international borders to successfully collect the data needed to better understand human behavior and energy. polar bears when they spend the summer in the country.
“As land use increases, the expectation is that we are likely to see this increase in famineespecially among the teenagers and the females with puppies,” the expert concludes.