When the king penguin population was last counted on Île aux Cochons, or Pig Island, back in 1982, there were 500,000 breeding pairs, making it the largest such colony in the world (above). Now, just 3 decades later, the population has plummeted by an alarming 90%, The New York Times reports. Researchers noticed the decline when they were flying over the island in 2016. They then used satellite images taken over 30 years to estimate that just 60,000 breeding pairs were left, they report this month in Antarctic Science. They suggest that climate change, disease, competition for resources, and an El Niño event in 1997 may all be reasons for the decline, which could eventually push the penguins onto the endangered species list.