HOLLYWOOD has turned them into the cartoon stars of the film Happy Feet, but the real life story of the rockhopper penguin is not such a happy tale, scientists have discovered.
Millions of the birds are disappearing in a "sinister and astonishing" phenomenon that is baffling biologists.
In just six years their numbers have fallen from 600,000 to 420,000 in the Falkland Islands - one of its few remaining strongholds - according to the latest survey by Falklands Conservation.
The decline equates to a drop of about 30 per cent, although the Falklands population is thought to have dipped by about 85 per cent since 1932, when there were more than 1.5 million birds.
It is thought that global warming may be behind its decline, as warmer seas are less productive and the penguins may not be able to find enough food to eat, but researchers admit they have not yet established the reasons.
Dr Geoff Hilton, an RSPB biologist who has studied the species, said: "It's actually quite rare in conservation that we don't know why a species is declining.
"All around the world from New Zealand to the Falklands there used to be all these huge colonies. Populations separated by 1,000km of sea are all crashing.
"It's an astonishing decline, the populations have just crashed over the last few decades and we really don't know why. It's quite sinister, we have got millions of penguins just disappearing."
He analysed rockhopper feathers dating back to the 19th century from stuffed animals in museums and discovered in warm years the penguins feed "lower" on the food chain, on krill and squid rather than fish. This less nutritious food might be the reason they are suffering. In several years, rockhoppers have starved to death in their hundreds of thousands during the annual moult, when they are unable to swim and, therefore, feed because their feathers are not waterproof.
Other penguins have suffered, but have bounced back, while the rockhoppers only seem to stabilise before falling again. A red tide of toxic algae in the Falklands also killed thousands in 2002-3.
Dr Hilton said: "There must be some major big thing going wrong in the eco-system. We did see some clues [in the feathers study] and the finger is tentatively pointing at global warming."
In Happy Feet, a rockhopper penguin called Lovelace, voiced by Robin Williams, is a self-proclaimed prophet who also narrates the story.
The film has proved a huge hit.
The research was funded by the Royal Zoological Society of Scotland, which runs Edinburgh Zoo. Roslin Talbot, the zoo's head keeper of penguins, said: "It is very serious for them. Zoos generally have found them quite difficult to breed. They are choosy when they go to pick their mates and they like very specific places to nest."
Grant Munro, the director of Falklands Conservation, said there were fears that rockhoppers might become extinct. "If the present situation were to carry on then it's not a particularly great forecast. It doesn't look like they are suddenly going to start increasing in numbers," he said.
"In the Falklands, they are part of everyday life. If you head down to the beach you are going to see penguins."
And they are amazingly tame and inquisitive.
"You are not perceived as a risk so they will come over and say hello."