Southern Elephant Seals (Mirounga leonina) are massive – mature males grow to 5.8 metres (19 feet) long and weigh up to 4,000 kilograms (8,800 pounds), and are typically five to six times heavier than females. Elephant Seals are true seals, and are unable to walk with their flippers and have no external ear visible. Mature bull Elephant Seals arrive on the beaches of South Georgia island in August, and pregnant females follow in September or October to give birth to a single pup. The “beachmaster” males round up as many females as they can in harems, and aggressively defend them against “bachelor” males. Pups are weaned in about a month, and are left behind as their mothers and dominant bulls return to sea. Subadult male Elephant Seals often play-fight, testing each other’s strength to establish a dominance hierarchy, as were these two at Grytviken, South Georgia.