A rare pale penguin and seals have been spotted hanging out on South Georgia Island in the southern Atlantic, with a rare genetic condition causing them both to stand out.
South Georgia is a remote island located nearly 2,000 kilometers (1,200 miles) off the southern tip of South America. It has no permanent human inhabitants (other than researchers) but hosts a wealth of cold-loving creatures like king penguins and Antarctic fur seals.
Photographer Jeff Mauritzen was there in March on a National Geographic expedition to the island when he saw the unusual animals, and managed to get a few snaps of them. None of the creatures seemed to be affected by their anomalies, he told National Geographic, and were not treated any differently by their darker-colored brethren.
Although rare, there are actually a few different conditions that affect the pigments in animals (including humans). It is thought the king penguin here, which is a pale browny-gray, has a form of leucism, an umbrella term that refers to partial loss of pigment in skin, feathers, and fur but does not affect the eyes.
Albinism, which is much more recognizable, results in white skin, feathers, and fur, as well as red or blue eyes due to an absence of the enzyme tyrosinase, which is involved in the production of melanin, the pigment that gives us black coloring. However, leucism can create a myriad of colorings from blonde to the taupe seen here. It looks like the penguin has a mutation in the gene that produces eumelanin, the type of melanin responsible for brown and black pigment (the other type is pheomelanin, responsible for red hair), as only its dark feathers have been affected.
It’s also noticeable that it kept its vibrant yellow feathers. This is because colors that contain carotenoids – yellows – are not affected by the condition.
It wasn’t just pale penguins that Mauritzen captured on camera though; as you can see on his website, he also spotted some white seals and pups. In fact, South Georgia Island has an unusually high population of seals with leucism. Research suggests this is probably due to at least one leucistic Antarctic fur seal being present on the island when the seals were close to extinction thanks to uncontrolled hunting throughout the 19th and 20th centuries. It's even thought this can be pinpointed to a single pale seal spotted amongst the population of 60 in 1933, just after it had reached its lowest point and before a population boom. Leucism is an inherited condition and as 95 percent of the world's population of fur seals breed on this island, the founder effect may be at play; when a new population is formed from a small number of individuals certain genetic traits are more prevalent than they normally would be.
Although there is a danger that animals with leucism, albinism, and melanism are more at risk from predators as their lack of markings or camouflage makes them easier to spot, there is little evidence that fellow animals treat them any differently or they are less successful at breeding. Perhaps they occur more often than we think and they're just better at hiding from the camera?