[redboiling]

Where do you get this from (that polar bears need to get off the ice to raise cubs)? Here is from a site on polar bears:

"Polar bears depend on the presence of ice for access to seals. In summer, when the floes retreat north, polar bears will travel hundreds of miles to maintain contact with their prey.

Between summer and winter the amount of ice-covered water can change rapidly. Polar bears learn to follow the ice to stay with their food source.

Those polar bears that are stranded on land in summer must stay there until the ice forms again in fall. On land, the bears face lean times, for they seldom catch seals without a platform of ice."

[JustDoItAlways]

Do a little reading on polar bear behavior before you assume they spend their entire life on the ice.

Cubs are sometimes born in a den made on the permanent icepack. Most of the time, they are born in a den made on on land.