Antarctica’s Cape Crozier is not somewhere tourists or even scientists usually go. To protect one of Earth’s largest Adélie penguin colonies, the area requires special permission to visit.
Some estimates have put as many as 600,000 of these 10-pound, flightless birds gathering on this desolate coast, with Mount Terror looming in the sky above.
And yet, earlier this winter, on a National Geographic tourist expedition, photographer Jeff Mauritzen captured images of one penguin unlike any other—a pale animal that appeared as if some of its black feathers had been stripped of their color.
“Yes, it’s an isabelline, or leucistic, penguin,” confirms P. Dee Boersma, a penguin expert at the University of Washington in Seattle, by email.
“The penguin looks washed out or like it was bleached. It is a genetic mutation,” says Boersma, a National Geographic Explorer.
Unlike albinism, which occurs when a person or animal’s body produces no melanin, or pigment, leucism happens when those pigments are prevented from being distributed to all the body parts. Leucistic and isabelline are sometimes used interchangeably to describe the pale brown or blonde coloration of penguins with this condition.
Surprisingly, this is not Mauritzen’s first rodeo when it comes to leucistic penguins.
“I’ve seen millions of penguins,” says Mauritzen, who leads National Geographic photography tours. “But I’ve seen two of these now.” (See pictures of other unusually colored animals.)
In 2019, Mauritzen photographed a leucistic king penguin on South Georgia Island, which is 1,200 miles from the tip of South America.
The most oddly colored species
Leucistic penguins are rare, but not unheard of. In fact, penguins with this condition have been identified in a number of species, including chinstrap, rockhopper, and macaroni penguins. (Read: “Rare pale-colored penguin and seals spotted on remote island.”)
What’s more, a 2000 study revealed that some penguin species are more likely to display leucism than others.
“Adélie penguins were among the most common,” says Boersma, who has also witnessed leucism in this species.
In all, gentoo penguins were most likely to be leucistic, with an occurrence rate of one in 20,000. Adélies were next, with one in 114,000 animals showing leucistic traits, while chinstraps came in third at one out of every 146,000 birds.
So far as scientists can tell, penguins with leucism live normal lives, and are neither shunned by their peers nor targeted by predators at higher rates. (Read: “Yellow penguin spotted in Antarctica—here’s why it’s so rare.”)
“Nature is just continuously surprising us,” says Mauritzen.
“For somebody like myself, who’s been to many, many places and had many amazing wildlife encounters, seeing something like that still is just so exciting and astonishing.”