(Image credit: Kennedy News and Media/Yves Adams)

Black and white tuxedos may be the conventional dress code in the penguin world, but one dapper individual is breaking the status quo with a fashionable yellow coat.

A wildlife photographer captured images of the rare penguin on a remote island in South Georgia in December 2019 and recently posted the photographs. A king penguin “walked straight towards us in the middle of a chaos full of elephant seals and Antarctic fur seals, and thousands of other king penguins,” Belgian photographer Yves Adams wrote in an Instagram post. “How lucky could I be!”

At the time, Adams was leading a two-month photography expedition across the South Atlantic and had stopped at a beach in South Georgia. As he was unpacking safety gear, he saw a flutter of penguins swimming toward shore; one individual immediately caught his eye.

“I had never seen or heard of a yellow penguin before. There were 120,000 birds on that beach, and this was the only yellow one there,” Adams told Kennedy News and Media. “We all went crazy when we realized it. We dropped all the safety equipment and grabbed our cameras.”

King penguins (Aptenodytes patagonicus), like the closely related emperor penguins (Aptenodytes forsteri), typically sport black-and-white fur with a splash of yellowish-gold on the neck. The yellow pigments are “unique to penguins,” although not all species have them, according to the Australian Antarctic Program.

This particular penguin appears to have kept its yellow feathers, but lost its dark ones, which are normally colored by a blackish-brown pigment known as melanin.

Penguins with unusual plumage are relatively rare, and it can sometimes be difficult to identify the cause behind the odd colors just by looking at the penguins, according to the Australian Antarctic Program. Some unusual colorations can be due to injury, diet or disease, but many cases are due to mutations in the bird’s genes. Such mutations can cause, for example, “melanistic” penguins whose typically white parts are black, and “albinistic” penguins that have no melanin and are therefore white.

The yellow penguin has lost its melanin, a pigment that turns some of its feathers black.   (Image credit: Kennedy News and Media/Yves Adams)

Adams told Kennedy News that the yellow bird has a genetic condition known as leucism in which only part of the melanin is lost.

Dee Boersma, a conservation biologist and professor at the University of Washington who was not part of the expedition, agreed. “This penguin is missing some pigment, so it is [leucistic],” Boersma told Live Science in an email. “True albinos have lost all pigment.” (Boersma said the bird has a brown head and therefore must have retained some pigment.)

Still, others disagree.

“I wouldn’t call the bird leucistic,” because the penguin appears to lack melanin, said Kevin McGraw, an integrative behavioral ecologist at Arizona State University who was also not part of the expedition.

“It looks albino from the perspective that it lacks melanin” in its plumage, legs and eyes, McGraw said. Still, “we would need feather samples for biochemical testing if we wanted to unequivocally document” whether melanin is present, he said.

Animals can be albino but still have a pigment other than melanin, he added.

The penguin has lost the carotenoid or yellow-orange-red pigment from its beak and the melanin pigment from its feathers, although it retains the yellow pigment in its feathers. So the genetic and cellular machinery for some pigments has been disabled, while others have not. “I don’t know of many other images or birds like this,” McGraw said. “I was fascinated by this photo.”

Such strangely colored birds are rare, and probably for a reason.

Penguins use body and plumage color for a variety of functions, including mate selection, camouflage or sun protection, McGraw said. “It is conceivable that such color aberrations could affect both survival and reproduction.”

The team was lucky that the yellow penguin landed close enough to be able to “get this sight of a lifetime,” Adams said. “Our view wasn’t blocked by a sea of ​​huge animals. Normally, it’s almost impossible to move on this beach because of all of them.