Cruel climate dilemma for King penguins: feed or breed
Global warming is on track to wipe out 70 percent of the world's King penguins by century's end, putting the regal birds on a path towards extinction, researchers warned Monday.
As climate change drives away the fish and squid upon which the flightless creatures depend, the penguins must swim further afield to find sustenance for their hungry hatchlings on land.
"For most colonies, the length of the summer trips by parents to get food will soon become so long that their offspring could starve while waiting," said Celine Le Bohec, a population ecologist at the University of Strasbourg/CNRS in France and co-author of a study in Nature Climate Change.
"If global warming continues at its current pace, the species may disappear," she told AFP.
Le Bohec and colleagues calculate that 1.1 million King penguin couples will be forced to abandon their current breeding grounds -- mainly on the islands of Crozet, Prince Edward and Kerguelen, roughly halfway between the tip of Africa and Antarctica -- within decades.
On current trends, the planet will heat up three or four degrees Celsius compared to mid-19th century levels by 2100.
Even if humanity caps the rise of Earth's surface temperature at two degrees Celsius (3.6 degrees Fahrenheit) -- the target set in the 197-nation Paris climate treaty -- up to half of the iconic birds could be forced into exile without a clear destiniation.
The problem is that there are few suitable alternatives, creating a no-win, feed-or-breed dilemma.
"There are only a handful of islands in the Southern Ocean, and not all of them are suitable to sustain large breeding colonies," said lead author Robin Cristofari from the Centre Scientifique de Monaco.
- Nutrition conveyor belt -
At just under a metre (three feet) tall, King penguins -- whose black-&-white tuxedos are accessorised with orange bands around the neck -- are "serially monogamous", meaning they stay faithful to one mate each year.
The female lay a single egg, which incubates for nearly two months. Male and female take turns keeping it warm.
On land, the ungainly birds waddle or slide over ice on their bellies, pushing with flipper-like wings.
King penguins are picky about where they settle: they need tolerable temperatures year round, no winter sea ice circling the island, and a smooth beach of sand or pebbles.
Above all, they need an abundant, nearby source of food.
For thousands of years, that came from the Antarctic Polar Front, an upwelling from the Southern Ocean teeming with fish, squid and other comestibles.
With climate change, however, this conveyor belt of nutrition has been drifting southward.
Analysing the King penguin geonome, the international research reconstructed fluctuations in their population over the last 50,000 years. Past episodes of natural climate change, they found, also shifted marine currents and the distribution of sea ice, and the birds always managed to adapt.
"King penguins were able to move around quite a lot to find the safest breeding ground," explained senior author Emiliano Trucchi, an evolutionary geneticist at the Universities of Ferrara and Vienna in Italy.
But this time, he added, manmade climate change is too abrupt and rapid.
To make matters worse, King penguins are dealing with competition from industrial fishing boats that scoop up fish by the tonne, and other species of penguins, such as Chinstrap, Gentoo and Adelie.