If you ask the internet, penguins are pretty much perfect as they are: cute, curious, and clumsy. But the truth is, the “perfect” penguin might not always take the same form.

Since 1983, biologist P. Dee Boersma has been studying the world’s largest colony of Magellanic penguins at Punta Tombo, Argentina, and has found that as environmental conditions shift, the penguins show a resilience to those changes. Boersma and her colleagues have measured a lot of penguins. And they’ve been tracking whether and how everything—from their bills to their flippers to their feet—has been changing over time.

“It’s kind of like a big general census,” says Laura Koehn, a doctoral candidate in fisheries science who worked with Boersma’s team as an undergraduate.

By marking penguins with ID bands, the researchers tracked how successful each was at raising its young, which traits were passed down through the generations, and whether certain parental traits, such as a longer bill or shorter feet, led to a boost in survival for a penguin’s offspring.

Read the full article in Hakai Magazine.