It is the third largest land mammal , judging by its weight , which is between between 1 Â 1\/2 and 3 tonnes . The white rhinoceros weighs 1 Â 1\/2 to 3 Â 1\/2 tonnes , and the three species of elephant weigh 3 to 9 tonnes . It is the third-largest land mammal by weight ( between 1 Â 1\/2 and 3 tonnes ) , behind the white rhinoceros ( 1 Â 1\/2 to 3 Â 1\/2 tonnes ) and the three species of elephant ( 3 to 9 tonnes ) .