Penguins in Peril

The world’s largest colony of king penguins has shrunk by 90%, researchers say.

Thirty years ago, there were some 2 million king penguins on France’s remote island of Ile aux Cochons. It is located in the Indian Ocean, between Africa and Antarctica. But satellite pictures show that the population has almost entirely disappeared. A recent study published in the journal Antarctic Science estimates that only 200,000 of the penguins are left.

The reason for the decline is unknown. Scientists say disease could be a factor. Another reason could be overcrowding. King penguins relocate when they can no longer compete for food.

But an even more alarming trend may be playing a part: climate change. Research has shown that rising greenhouse gases are taking a toll on penguin populations. Penguins like to hunt and fish in icy waters. But as air temperatures get warmer, so do the oceans. The penguins have to swim farther away from the island to reach cold water. That means hunting trips can take much longer. If the penguins don’t make it back to the island in time, their chicks starve.

A study published earlier this year predicted that 70% of all king penguins could vanish before the end of the century. “It is completely unexpected, and particularly significant, since this colony represented nearly one-third of the king penguins in the world,” Henri Weimerskirch told TIME. He is an ecologist at France’s Chizé Centre for Biological Studies. Weimerskirch says scientists plan to visit Ile aux Cochons next year. There, they will conduct more research. They hope to learn more about what is causing king penguins to disappear.