Life has never been easy for just-hatched Magellanic penguins, but climate change is making it worse, according to a decades-long study of the largest breeding colony of the birds.

The chicks are already vulnerable to predation and starvation. Now, the study at Punta Tombo, Argentina, found that intense storms and warmer temperatures are increasingly taking a toll.

“Rainfall is killing a lot of penguins, and so is heat,” said P. Dee Boersma, a University of Washington scientist and lead author of the study. “And those are two new causes.”

Climate scientists say more extreme weather, including wetter storms and more prolonged periods of heat and cold, is one impact of a climate that is changing because of emissions of greenhouse gases in the atmosphere. While monitoring the penguin colony, Dr. Boersma and her colleagues also documented regional temperature changes and increases in the number of days with heavy rains.