REUTERS/Ho, Staff photographer
A polar bear nestles into a hole it dug in the 15 tons of snow covering the Polar Bear Plunge habitat at the San Diego Zoo May 19, 2006. Snow was one of many enrichment items zookeepers offered the Zoo??s bears during Bear Awareness Week as a way to entice visitors to visit each of the five bear species found on grounds to educate the public about natural bear behaviors, what threatens their survival in the wild and the conservation work the San Diego Zoo is doing for bears.