Aurora, a one-year-old female polar bear cub, plays in a swimming pool which was filled with water for the first time this spring, at the Royev Ruchey zoo in Russia's Siberian city of Krasnoyarsk, April 14, 2011. Two female wild polar bear cubs were found in Russia's Taimyr Peninsula on the Arctic Ocean coast in May 2010 and were later housed at the zoo in Krasnoyarsk. [Photo/Agencies]

A boy displays a horse's teeth on a farm in the outskirts of Havana April 10, 2011. [Photo/Agencies]

A stork is pictured after it was set free on the great Hungarian plains in Hortobagy, about 180 km (112 miles) from Budapest, April 6, 2011. Every year, employees of Budapest Zoo capture storks that are too young to make the journey south to Africa before the onset of winter in order to help them survive the cold months before setting them free in warmer weather. [Photo/Agencies]