Polar bears are considered by many to be marine mammals. The name Ursus maritimus means maritime bear. Their preferred habitat is the pack ice of the Arctic Ocean. The ice edge and pressure ridges where fractures and refreezing occur provide the best hunting ground. Bears will travel as much as 1,000 km north and south, as the ice melts and freezes. During summer bears may remain on islands or coastlines with landfast ice, drift on ice flows, or get stranded on land where they are forced to endure warm weather. (DeMaster and Stirling, 1981; Nowak, 1999; Stirling and McEwan, 1975)
- Nowak, R. 1999. Walker's Mammals of the World. Baltimore and London: The Johns Hopkins University Press.
- DeMaster, D., I. Stirling. 1981. *Ursus maritimus*. Mammalian Species, 145: 1-7.
- Stirling, I., E. McEwan. 1975. The caloric value of whole ringed seals (*Phoca hispida*) in relation to polar bear (*Ursus maritimus*) ecology and hunting behavior. Canadian Journal of Zoology, 53: 1021-1027.