Walker, a 58 stone (368 kg) polar bear, chases a plastic helmet in a pond on his third birthday at the Highland Wildlife Park in Kincraig, Scotland December 7, 2011. Walker was born in Rhenen Zoo in Holland and came to live at the Highland Wildlife Park after his aunt, Freedom, became pregnant and needed space to retire to her cubbing den. Winds of up to 70mph are expected to hit Scotland today, and snow in the Highlands is expected to be deeper than 10cm in places. [Photo/Agencies]

Walker, a 58 stone (368 kg) polar bear, chases a plastic helmet in a pond on his third birthday at the Highland Wildlife Park in Kincraig, Scotland December 7, 2011. [Photo/Agencies]