Polar Bears . . . Where? Statistics & Probability Article for Students

Even though they’re excellent swimmers, polar bears need solid ground to hunt for food. Their ground of choice? Arctic sea ice! By prowling on the frozen ocean ice, polar bears can hunt for seals and other marine life. Sea ice has historically covered all of the Arctic Ocean for most of the year. But it’s rapidly melting and decreasing in area, which means polar bears have less space—and time—to hunt.

That’s why scientists were startled when they found a potentially new subpopulation of polar bears in southeast Greenland. Polar bears need stable sea ice for about six months to ensure they get enough food before hunkering down for the winter. But these bears were surviving with as little as three months of sea ice! When the government of Greenland commissioned a study on the polar bears, Inuit hunters drew maps to help researchers find the elusive group.

Polar bears are excellent swimmers. But they still need solid ground to hunt for food. The bears hunt on big blocks of ice floating on the Arctic Ocean. From there, they can catch seals and other marine life. In the past, sea ice has covered the Arctic for most of the year. But more ice is now melting in the summer because of climate change. That means polar bears have less space and time to hunt.

Polar bears usually need sea ice for at least six months. That gives them time to find enough food before winter. So scientists were startled when they found a group of polar bears in southeast Greenland. These bears were surviving with only about three months of sea ice! The government of Greenland requested a study on these unique polar bears. Local Inuit hunters drew maps to help scientists find the group.

Courtesy of Kristin Laidre

Scientist Kristin Laidre studies a polar bear up close.

“They’re living in a really interesting way, and there’s a lot we can learn from how these bears managed to live completely cut off from other polar bears for a few hundred years,” says Kristin Laidre, a principal scientist at the Polar Science Center at the University of Washington. She was one of the lead researchers studying the Greenland polar bears.

Laidre hypothesizes that polar bears first arrived in southeast Greenland after being caught on sea ice that traveled down the country’s eastern coast. After hundreds of years, they’ve become genetically distinct from other subpopulations of polar bears. The Greenland bears hunt on sea ice when it is available and on freshwater ice that breaks off from glaciers for the rest of the year. “For the polar bear, ice is ice,” Laidre says. “It can be giant icebergs down to small chunks of floating ice.” When that ice forms a stable hunting platform, the bears will use it.

Polar bears are still in danger. Climate change is causing the ice they need to survive to disappear. “This study doesn’t change what we think about polar bears in the future,” warns Laidre. “But it could tell us something about how polar bears could hang on as a species.”

“They’re living in a really interesting way,” says Kristin Laidre. She’s a scientist at the Polar Science Center at the University of Washington. She helped lead the study of the Greenland polar bears. “There’s a lot we can learn from how these bears managed to live completely cut off from other polar bears,” she adds.

Scientists aren’t sure how polar bears first arrived in southeast Greenland. Laidre suspects they got caught on sea ice that floated down the coast of the country. After hundreds of years, they’ve become different from other polar bears. The Greenland bears hunt on sea ice when it is available. But for the rest of the year, they hunt on ice that breaks off from glaciers on land. “For the polar bear, ice is ice,” says Laidre. “It can be giant icebergs down to small chunks of floating ice.”

Polar bears are still in danger. If too much ice melts, the species will not survive. But knowing that they can use glacier ice is important, says Laidre. “It could tell us something about how polar bears could hang on.”

Use the graph above to answer the questions about select polar bear subpopulations. Record your work and answers on our answer sheet.

Which subpopulation has the greatest range in estimated population size?

Which subpopulation has a range of approximately 1,500 bears?

What is the minimum and maximum estimate of bears in Foxe Basin? How does the point estimate compare with these estimates?

The newly discovered subpopulation in southeast Greenland has a point estimate of 234 bears, with a minimum 111 and a maximum of 462. How does this estimate compare with that of Kane Basin, which is on the western coast of Greenland?