The world’s largest colony of king penguins has declined by nearly 90 percent in 35 years, according to an alarming study published in Antarctic Science.

In the 1980s the colony on Pig Island in the sub-Antarctic archipelago of Crozet, about halfway between the tip of Africa and Antarctica, was estimated to contain some two million of the flightless birds.

But recent satellite images show the “colony has declined by 88 percent, from about 500,000 breeding pairs to 60,000 pairs,” the study found.

“It is completely unexpected, and particularly significant since this colony represented nearly one third of the king penguins in the world,” said lead author Henri Weimerskirch, an ecologist at the Center for Biological Studies in Chize, France, who first saw the colony in 1982.

The reason for the dramatic decline is still a mystery to the scientists.

Weimerskirch speculated that it could have been affected by a particularly strong El Nino weather event that warmed the southern Indian Ocean in 1997. The event temporarily pushed the fish and squid on which king penguins depend beyond their foraging range.

“This resulted in population decline and poor breeding success” for all the king penguin colonies in the region, Weimerskirch said.

While the other colonies in the region have bounced back, the one on Pig Island continues to decline, stumping scientists.

But until Weimerskirch and other researchers return to Pig Island — hopefully, he said, in early 2019 — they won’t know for sure.
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