One of a pair of grizzly bears enjoys himself with food on his 20-year-old birthday party at the Brookfield Zoo, west suburb of Chicago, the United States, on March 21, 2015. The grizzly bears, named Jim and Axhi, turn to be 20 on Saturday and the zoo officials celebrated their birthday with a special party. The bear brothers were born on the same day and made their way to the zoo in 1995 when they were orphaned in Alaska, and they have lived in the Brookfield zoo ever since. (Xinhua/He Xianfeng)