World’s Largest King Penguin Colony Declined 90% In 30 Years, Study Finds

A new research suggested the planet’s largest colony of king penguins has declined by nearly 90 percent in the last three decades.

The colony, which lies on the France's uninhabited Île aux Cochons between Africa and Antarctica in the Indian Ocean, was blanketed by more than two million penguins about a metre tall when scientists last visited the area, reports said.

The study used aerial photographs from a helicopter and satellite images to compare changes in the population size of the colony over the past 50 years. They found the population had declined by 88 percent over the past 35 years, from 500,000 pairs to 60,000 pairs.

Though many possible causes for the decline were also explored in the study, a definite reason for such a sharp decline in penguin population happened could not be reached.

Apart from highlighting the use of non-invasive techniques to monitor the population, the study also stressed how further research was required to determine the causes for the alarming population decrease.

The colony was known in the 1980s as the largest king penguin colony and the second largest penguin colony in the world.

“It is completely unexpected, and particularly significant since this colony represented nearly one third of the king penguins in the world,” Henri Weimerskirch, an ecologist at the Centre for Biological Studies in Chize, France, told The Guardian. He had first set his eyes on the colony in 1982.

The newly published study mentioned the population numbers can fluctuate extensively due to large-scale climatic events like the Sub-Tropical Indian Dipole and El-Niño Southern Oscillation.

El Ninos are cyclic, occurring after gaps of two to seven years. Global warming, which produced similar conditions, can amplify the effects of El Ninos.

In 1997, a strong El Nino weather event warmed the Southern Indian Ocean. This pushed the fish and squid to the south, which was beyond the range of king penguins, which in turn resulted in poor breeding success and population decline for king penguin colonies in the region, Weimerskirch said.

Yet another reason, according to the study, might have been the partial relocation of the colony that was first noted in 2016 during a helicopter flight. The smaller colony nearer to the beach was on the penguins’ access route to the large colony. It was present in the 2005 satellite images as well as in the 2015, 2016 and 2017 satellite images. But it wasn’t seen during ground observations in1974 and 1982.

Overcrowding might have been another contributor.

“The larger the population, the fiercer the competition between individuals,” France’s National Centre for Scientific Research, which funded the study, said. “The repercussions of lack of food are thus amplified and can trigger an unprecedented rapid and drastic drop in numbers.”

Infection from avian cholera, which affected seabirds, including some king penguins on nearby Marion and Amsterdam Islands, might be another reason for the population decline. But researchers could not confirm anything until they studied the situation further.

The king penguin, second in size only to the emperor penguin, breeds on the more temperate islands north of the Antarctic coast. They are known to be homebodies, which means the species does not migrate. The adults might go to the sea for days at a time searching for food, but they always return to their homes.

Currently, the king penguins are put under “least concern” in the Red List of Threatened Species conservation status. But the recent study might prompt a re-evaluation.