Due to climate change, the polar bear faces the risk of extinction

Arabia Weather - A new scientific study showed a warning about the increasing risk of extinction of polar bears, as they appear to be unable to adapt to extended summer periods in the Arctic as a result of global climate change. Scientists point out that the longer this huge predator stays on land away from sea ice, the more likely it is to be at risk of starvation.

Polar bears are found in Arctic regions such as Canada, Alaska, Russia, Greenland, and Norway. The polar bear spends most of its time on the sea ice, where it hunts seals, rests, reproduces, and cares for its young.

The study, the results of which were published in the British newspaper "Daily Mail", reported that 20 polar bears were closely monitored by scientists during three summer weeks, as they tried different methods to preserve energy reserves, including resting and searching for food. However, almost all of them lost weight quickly, with the average weight loss being about 2.2 pounds per day, according to the study results.

Some experts have speculated that polar bears may begin to adapt to longer, ice-less seasons as a result of global warming, by adopting behaviors similar to those of their grizzly bear relatives, such as resting or eating ground food. However, the new study showed that polar bears that tried versions of both strategies had little success.

“None of the strategies would allow polar bears to remain on land beyond a certain period of time,” said Dr. Charles Robbins, co-author of the study and director of the Bear Center at Washington State University. He added: "Even bears that were searching for food lost weight at the same rate as those that were resting."

He added: "Polar bears are not just grizzly bears with white coats. They are completely different." In general, male polar bears are larger than grizzly bears, which can reach 10 feet in length and weigh about 1,500 pounds (about 680 kilograms), compared to grizzly bears that are eight feet tall and weigh about 800 pounds (about 363 kilograms).

To maintain their massive size, polar bears rely on the energy-rich fat found in seals, which they prefer to hunt on the ice.

Very little was known about the energy expenditure and behavior of polar bears when confined on land, so researchers used collars equipped with video cameras and GPS to track their movement as they summered in the western Hudson Bay region of Manitoba, Canada.

The research team wanted to see what specialized ice hunters eat and how they behave during their time on land when their usual prey is unavailable. The researchers also weighed the bears before and after the observation period, and measured their energy expenditure. “We found real diversity in bear behaviors, and as a result, we saw a variety of energy expenditure,” said lead study author Dr. Anthony Pagano, a wildlife biologist with the US Geological Survey's Polar Bear Research Program.

He noted that many adult male polar bears simply spend their time lying down to conserve energy, burning calories at rates similar to hibernation. While others actively forage for food, feeding on bird and caribou carcasses as well as berries, kelp and grasses. Overall, the researchers found a five-fold increase in energy expenditure among adult males who were relaxed 98% of the time compared to active ones who walked 205 miles (330 kilometers).

Some adult females spent up to 40% of their time searching for food, but the researchers found that all this activity did not pay off. "Although terrestrial foods provided some biological benefits, in the end, the bears had to expend more energy to access those resources," Dr. Pagano said. Three polar bears took a long swim, with one of them swimming an estimated distance of 175 kilometers (about 110 miles) across the bay.

Two bodies were found in the water, but none of the bears were able to capitalize on their swimming discoveries or make it back to land. Only one bear out of twenty was able to gain weight after a marine mammal was found dead on land. The study focused on the southernmost reaches of polar bears' range in western Hudson Bay, where climate warming is likely to have a greater impact on bears than in other regions of the Arctic. The region has seen the polar bear population decline by an estimated 30% since 1987.

The new study suggests that polar bears across the Arctic are at risk of starvation as the ice-free period continues to grow. "Because polar bears are forced onto land earlier, the period in which they gain the majority of the energy they need to survive is cut short," Dr Pagano said. “With increased land use, we are expected to see increases in famine, especially among adolescents and females with children,” he added.

Source: Agencies