The final opening weeks of the world’s fifth oldest zoo, Bristol Zoo Gardens was marked July 21 with the unveiling of a giant interactive gorilla sculpture.   The team behind the historic attraction, which will close on September 3, are encouraging visitors to make one final visit as part of a ‘BIG Summer Send-Off.’   The centrepiece of the final summer programme is ‘Wilder’, a specially-commissioned gorilla sculpture, which is taller than the largest giraffe ever recorded, and as…