Twin polar bear cubs Gregor and Aleut are pictured with their mother Vera while sitting outside in the sun in their enclosure at the zoo in Nuremberg march 23, 2011. The cubs were born on December 2, 2010. [Photo/Agencies]

A pair of Blue Herons sit in their nest in Vancouver, British Columbia March 23, 2011. The Blue Herons gather each spring to nest in the same area of Stanley Park. [Photo/Agencies]