animals Asian-elephant boulder brisles bristly calf Calves captive electric-fence elephant elephant-hide elephant-side elephants elephas-maximus fence fenced-in hair hairy herbivore Indian-elephant large largest-terrestrial-mammal mammal mammals play playful pushing rock rocks skin sociable strength strong texture textures tree-trunks trunk wiry wrinkled wrinkles young youngsters zoo animal close feeding grass Indian Nyberg Africa Botswana wild wilderniss