Various types of unusual penguins call Antarctica and the sub-Antarctic home, including penguins with different plumage colourations and hybrid penguins (offspring of cross species mating). Both hybrid penguins and penguins with non-standard plumage are relatively rare.
Unusual plumage colourations (or colour aberrations) can be caused by a variety of factors including injury, diet and disease, but many are due to mutations (alterations in genetic material). Some of those can be identified by just looking at a bird. However, the nature of others can really only be determined properly through genetic analyses.
Penguins may not have a wide range of colours, but plumage colour is still important. Plumage colouration can be a visual signal identifying a bird’s species, sex, age and even health.
Before penguins moult their plumage looks dull and almost brown. All feathers need to be replaced every year having been worn out by the sun, sea salt and other environmental factors. Once the penguins have undergone their annual moult, their plumage is soft and shiny, and the brand new feathers are deep grey or black.
Only some penguin species sport yellow feathers on their heads and chests, but all have a basically black and white body. The yellow pigments are unique to penguins. The dark colouration of penguin feathers is due to two pigments, called phaeomelanin and eumelanin, which are collectively known as melanins. At times, the plumage colouration of individuals is very different from the norm. It is often difficult to determine the type of mutation that has taken place just by looking at a penguin.
Melanistic and albinistic (albino) penguins
Colour aberrations range from ‘melanistic’ (a penguin whose normally white parts are black) to ‘albinistic’ (a penguin that lacks both melanins and is totally white). An albinistic penguin (or an albino) also lacks any pigments in its beak, skin and eyes, making these parts appear pink. Albinism is a serious condition for penguins. They usually do not live very long because they tend to become blind and can no longer fend for themselves.
There are also completely white penguins whose beaks and eyes are pigmented (not pink). These birds are ‘leucistic’ or leucinos. ‘Leucos’ is the Greek word for white. The mutation causing leucism enables the production of the pigments in the epidermis, but the mechanism to deposit the melanins into the feathers is faulty. Unlike in albinistic birds, not every pigment-producing cell is necessarily affected — meaning that penguins can be partially leucistic. The degree of leucism can range from just a few feathers to the entire plumage.
A relatively common aberration is simply known as ‘brown’. The appearance of the dark eumelanin pigment is altered so that the penguins appear brown and white rather than black and white. The brown feathers are very sensitive to sunlight and can fade over time. Brown birds may also have paler beaks and feet.
Mutations that can affect both melanins are called ‘dilution’. This mutation has many gradations as the feather colour depends on the degree of melanin reduction. The pigments themselves are not changed, but the amounts of pigments deposited are reduced. The result is that the black feathers are grey and the affected penguin has a washed out appearance.
Even more extreme than the dilute mutation is ‘Ino’. When this mutation occurs the black feathers are very pale brown and can look nearly white, especially in late summer. Over time, the plumage gets bleached by the sun making ino penguins apear white.