A rare white magpie? not quite
THIS RARE WHITE currawong, initially thought to be some kind of rare white magpie by visitors of the Royal Botanical Garden Sydney (RBGS), has a rare condition known as ‘leucism’, according to wildlife ecologist Dr. John Martin, who works at the RBGS.
“This Pied Currawong is rare because it has leucism but still has small patches of coloured feathers and yellow eyes. The plumage has a washed-out appearance instead of a complete lack of colour like an albino bird,” he said.
“Pied Currawongs tend to stay in the same areas year-round so it’s likely visitors have seen it before, but because it is currently breeding season for the species, sightings have increased over the past few weeks,” he added.
Pied currawongs differ from other currawongs thanks to their splashes of white; they’re mostly black with a little white on their tails and wingtips. These birds may superficially resemble magpies, but they have much less white in their plumage, and they have yellow eyes.
What is Leucism?
Leucism is a general term caused by defects in pigment cells during development. The hiccup in the genes result in either the entire surface (if all pigment cells fail to develop) or patches of body surface (if only a subset are defective) having a lack of cells capable of making pigment.
This defect differs from that of albinism, as the animal retains areas of normal colouring, such as the beak, legs and eyes. Leucism can also result in the ‘piebald’ effect sometimes seen in horses and pythons, where the lack of pigmentation only occurs in some areas.
Another contrast between albinism and leucism is in eye colour. Due to the lack of melanin production in both the retinal pigmented epithelium and iris, albino animals typically have red eyes. This is due to the underlying blood vessels showing through, while in contrast, most leucistic animals have normally coloured eyes.