Hungry penguins chase Antarctic's shifting krill

Waddling over the rocks, legions of penguins hurl themselves into the icy waters of Antarctica, foraging to feed their young.

Like seals and whales, they eat krill, an inch-long (2.5 cm) shrimplike crustacean which forms the basis of the Southern Ocean food chain.

But penguin-watchers said krill are becoming scarcer around the western Antarctic peninsula, under threat from climate change and fishing.