Just north of the Antarctic Peninsula, there’s a small, ice-covered island shaped like an elephant’s head. Each year, despite brutal winds and a landscape of crags, cliffs, and glaciers, hundreds of thousands of chinstrap penguins manage to nest on these shores, creating a living sea of black-and-white feathers.

“They’re like little mountaineers,” says Noah Strycker, an ornithologist and graduate student at New York’s Stony Brook University. “They climb up 300 to 400 feet in some places.”

But when Strycker and his fellow scientists spent 11 days counting chinstrap nests as part of a scientific survey this January, they discovered tens of thousands of penguins were missing.

“Comparing it to the number from 50 years ago, we’ve found a 56 percent drop