SYDNEY, AUSTRALIA - APRIL 20:  Prince William, Duke of Cambridge holds  Prince George of Cambridge as Catherine, Duchess of Cambridge gives him a toy bilby during a visit to the Bilby Enclosure at Taronga Zoo on April 20, 2014 in Sydney, Australia. The Duke and Duchess of Cambridge are on a three-week tour of Australia and New Zealand, the first official trip overseas with their son, Prince George of Cambridge.  (Photo by Chris Jackson/Getty Images)