Books in the Bertie the Buffalo series

Bertie the Buffalo is having fun on the farm where he lives in Scotland. Then a mysterious letter arrives inviting him to represent Scotland in the Worldwide Games. Bertie and his friends fly to Tokyo where they meet new and exotic animals and try to win first prize in all the different events. Bertie is sad when he isn't winning any medals but finds out if he works together with his friends, he will be a winner in the end.