Scientists have found troves of mummified penguins buried deep in the sediments of Long Peninsula, East Antarctica.
Researchers reported the Adelie penguins probably perished in two die-offs caused by extreme climatic events that persisted over decades. These weather conditions, they caution, may become more common as our planet warms.
"It is quite likely that global climate warming caused enhanced precipitation, which led to the tragedy," Liguang Sun of the University of Science and Technology of China—one of the authors of the research published in the Journal of Geophysical Research: Biogeosciences—told Live Science.
The research team stumbled on the penguin mummies back in January 2016. They found hordes of preserved carcassses—some 10 to 15 per 10² feet in the long-dead colonies. "They consist of well-preserved dehydrated mummies, mostly intact or partially intact with skeletal structure, skin and feathers," the team wrote in their paper. "Most of the carcasses are chicks, as judged by size and porous bone surfaces."
The penguins likely died in two waves around 750 and 200 years ago, radiocarbon dating suggests. Evidence from sediments around the mummies revealed extreme climatic events that took place over decades. Periods of heavy rainfall and snow were particularly dangerous for the young chicks, the authors wrote.
"Unlike adult penguins that have feathers to insulate them from cold water, downy chicks lack waterproof plumage," they explained, "and when exposed to rain and snow, chicks can suffer from high mortality and slow growth due to hypothermia."
Unfortunately, mass penguin deaths aren't consigned to history. In 2013-14, all of the chicks born to a group of about 34,000 breeding penguins died on Petrel Island. This complete die-off was linked to extreme environmental conditions. Tragically, a similar breeding failure occurred in 2016-17.

Climate change continues to threaten Antarctic penguins, Sun told Live Science. "Generally, it is believed that the current global warming trend will continue or even worsen... Humankind needs to do more and slow the current global warming trend."
In happier animal news, scientists recently discovered three new species snailfish swimming five miles below the surface of the Pacific Ocean in the Atacama Trench. Researchers also captured extremely rare footage of a weird, spider-like crustacean called a munnopsids.
Elsewhere in the Pacific, a California aquarium recently captured incredible footage of hundreds of hungry dolphins racing through the sea in search of fish. "There are few things more magical in this world than hundreds of dolphins racing through the wild Monterey Bay on a foggy fall morning," a tweet from the aquarium said.