Penguins are one of the most iconic, beloved creatures in the animal kingdom. Contemplating a future without them is unthinkable, but with continued increasing global temperatures, rapidly declining populations across the board is a reality.

From the Emperor penguins of Antarctica to the yellow-eyed penguins of New Zealand, scientists have been monitoring the dapper birds’ struggle to adapt to climate change as rising sea temperatures result in a decline in sea ice, loss of habitat, and lack of food.  

However, penguin colonies are often quite remote and inaccessible so studying them can be a challenge. A startling new study on what was once thought to be the world’s largest King penguin colony has revealed that dramatic changes to a population can happen in a worryingly short time if we're not paying attention, and that population estimates can be wildly inaccurate.

Since the 1960s, the King penguin colony on the Île aux Cochons, in the Îles Crozet archipelago of the southern Indian Ocean had been the largest known King penguin colony, and the second largest of any penguin colony anywhere in the world.

The last time scientists visited the island, back in 1982, around 2 million penguins (about 500,000 breeding pairs) greeted them. Now, this latest study, published in Antarctic Science, has used satellite imagery and photographs taken from helicopters to estimate that that number was shockingly only about 200,000 (59,200 breeding pairs) in 2017 – a drop of 88 percent – and the researchers aren’t entirely sure why.

“It is completely unexpected, and particularly significant since this colony represented nearly one-third of the King penguins in the world,” lead author Henri Weimerskirch, who visited the island in 1982, told The Guardian.

To get an estimate of the colony size they calculated the area of the penguins’ territory by using satellite images, comparing the changes to the terrain since the 1960s. These showed the penguins’ territory had drastically shrunk thanks to encroaching vegetation, the monitored changes even allowing them to pinpoint the start of the population decline to the 1990s.

This coincides with a major El Niño event that occurred in the southern Indian Ocean in the 1990s, that had a documented effect on the foraging capacity of another colony 100 kilometers (62 miles) away, that dwindled quickly.

The researchers suspect a similar thing happened here; a drop in food availability sparks competition between animals, slowing the growth of the population as a whole, and actually resulting in a huge population decline.

There is a possibility that Avian cholera, which is ravaging many other island populations in the Indian Ocean, may also have a hand in it, however, the researchers are unsatisfied by this as an explanation for such a drastic and rapid decline, so field investigation plans are underway. 

All is not lost though, other King penguin colonies are thriving elsewhere, and scientists even recently discovered a massive previously unknown colony of Adélie penguins on the Danger Islands thanks to NASA satellites.