Long distance route orientation of female Polar bears (Ursus maritimus) in spring

Mammals in a patchy environment are often required to make regular spatial movements in order to obtain necessary resources. Polar bears (Ursus maritimus) are known to move distances of several hundred kilometres to locate favourable feeding areas or suitable habitats for female maternity denning. This paper describes the routes followed by adult female Polar bears in spring from a region in north-eastern Manitoba, Canada, where they had denned over winter, to the sea ice of Hudson Bay where they could hunt seals. Over a five-year period, 74 tracks in snow were followed for a total distance of 1081 km. Most tracks ( n = 64) were made by adult females accompanied by recently born cubs-of-the-year. These family group tracks followed relatively parallel and straight courses toward the sea with a mean heading of 39° but did not follow the shortest straight line distance to the sea. The remaining tracks were made by solitary bears, probably adult females. These tracks had a mean heading similar to that of family groups but travelled more convoluted courses. Solitary bears also frequently dug snow caves and multiple shallow snow pits along their routes, structures never observed along the routes of family groups.