Climate change is likely to have a devastating impact on king penguins if greenhouse gas emissions continue at their present rate, scientists have warned.
Seventy per cent of the birds - around 1.1 million breeding pairs - may disappear or be forced to find new homes before the end of the century.
Just under half of the world's population, breeding on the Crozet and Prince Edward islands in the southern Indian Ocean, were expected to lose their habitat completely.
Those from the Kerguelen, Falkland and Tierra del Fuego islands, making up a fifth of the total, were likely to experience strongly altered habitats.
King penguins can only shift breeding grounds in a stepping-stone manner, hopping between available islands.
Lead researcher Robin Cristofari, from the Hubert Curien Multidisciplinary Institute in Strasbourg, France, said: "The main issue is that there is only a handful of islands in the Southern Ocean and not all of them are suitable to sustain large breeding colonies."
The scientists, whose findings appear in the journal Nature Climate Change, simulated the penguins' past habitat shifts and identified future vulnerable areas.
For millennia, the birds have relied on the Antarctic Polar Front, an upwelling in the Southern Ocean that has concentrated enormous quantities of fish in a relatively small area.
Due to climate change this area is now drifting south away from the islands where most of the birds live.
Parent penguins are being forced to swim further to find food for their chicks.
The study predicts that for most colonies the length of the trips will soon exceed the chicks' resistance to starvation.