Bears Spar (image) University of Washington Caption Two male polar bears playfully spar near Hudson Bay, where sea ice melts in the summer and then reforms in the autumn. The bears need the ice in late summer and fall to be able to reach their prey, primarily seals. Credit Steven C. Amstrup, Polar Bears International Usage Restrictions News use only, with credit Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.