"Polar bear cubs forced to swim long distances with their mothers as their icy Arctic habitat melts appear to have a higher mortality rate than cubs that didn't have to swim as far, a new study reports.

Polar bears hunt, feed and give birth on ice or on land, and are not naturally aquatic creatures. Previous reports have noted individual animals swimming hundreds of miles (kilometers) to reach ice platforms or land, but this is one of the first to show these swims pose a greater risk to polar bear young.

'Climate change is pulling the sea ice out from under polar bears' feet, forcing some to swim longer distances to find food and habitat,' said Geoff York of World Wildlife Fund, a co-author of the study.

York said this was the first time these long swims had been quantitatively measured, filling a gap in the historical background on this iconic Arctic species."

Deborah Zabarenko reports for Reuters July 19, 2011. [2]