Adelie penguins (Pygoscelis adeliae), the archetypal 'waiter-in-a-suit' penguins, are one of nature's victims. They face, among other predators, one of the most efficient killing machines: leopard seals. Adelies (45-55cm tall and weighing 3.6-4kg) breed on the Antarctic pack ice and by late summer the young are ready to leave the rookery. The parents feed them closer and closer to the water's edge and then stop feeding them altogether. Now a tense drama plays out. The hungry young penguins edge nearer to the sea, bunching up in their hundreds on the lip of the ice. Finally they leap. The lucky ones dodge under the ice and swim to freedom. For the patient, patrolling seals it is a time of plenty.