For just the second time, biologists have spotted a gentoo penguin with melanism, a genetic condition that results in unusually dark feathers.
A gentoo penguin with unusually dark plumage has been spotted in Antarctica. The bird is only the second gentoo penguin ever to be documented with melanism, a condition that causes the overproduction of dark pigments in birds’ skin and feathers.
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| This unusual gentoo penguin has exceptionally dark plumage Rocio Nigro, Anahi M. Silvestro, Mariana Juares and Pamela Di Marco |
Gentoo penguins (Pygoscelis papua), which live on the rocky islands surrounding Antarctica, typically have pale bellies and darker backs that camouflage them against predators while swimming. But in December 2022, researchers studying the species found and photographed an adult bird with strikingly different plumage.
Instead of white feathers on the underside of its wings, this gentoo penguin has all-black flippers. Its belly is a cookies-and-cream-like mixture of white and black, with a dark line from its throat to its feet. The bird’s feet, eyes, head and bill are normal in colour, and it appeared healthy and accepted by its colony mates.
The researchers concluded that the gentoo penguin had melanism, a genetic condition that causes an over-production of melanin, a group of pigments that gives birds their colour. The amount and type of melanin each bird produces can vary by species, diet and individual.
“Though penguin colouration is a long-term evolutionary strategy that helps penguins avoid predation, I do not think this penguin’s colouration places it at serious risk,” says Heather Lynch at Stony Brook University in New York, who wasn’t involved in the work. “Being a penguin is risky enough already.”
The penguin is the first of its colony, located in Hope Bay, Antarctica, to be seen with melanism. The only previously documented case of melanism in a gentoo penguin was in 1997 when researchers spotted a similar phenomenon in an individual living in a colony in Paradise Bay, Antarctica.
The discovery advances experts’ understanding of colour variation in penguins and shows that “penguins can use pretty cute natural sweaters, besides tuxedos”, says Júlia Finger at the University of the Sinos Valley in Brazil, who was not involved in the work.
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