Unusual coloured birds

26 April, 2009

Common Blackbird, partial albinism.
Common Blackbird, partial albinism.
Image: Megan Lomax
Source: Museum Victoria

Question: I have a family of black crows living in my garden I have recently noticed that one of them has started to develop some white feathers amongst the black feathers. Why is this?

Answer: To find out why your black crow would begin to develop white feathers, your question was referred to the Collection Manager of the Ornithology (Bird) section of the Museum. He has provided the following information...

There are five species of crows and ravens in Australia and they are generally black. You can tell the difference between a crow and a raven by looking at the base of their body feathers. The base of the body feathers is pale greyish in ravens and white in crows.

Ravens are the birds seen around Melbourne and its environs – the most commonly seen species is the Little Raven. The other species occassionally seen locally is the Australian Raven, but this species is uncommon or restricted to particular areas.

Pigment variations in birds are well known. When a dark-coloured bird exibits white feathers, it is called albinism; when a light-coloured bird exhibits black feathers it is called melanism.  Other colours shifts can also occur; feathers can appear as brown, cream, or even yellow. In the crows and ravens the principal colour shift is towards either white or brown with some creamy birds occasionally seen.

The incidence of birds being totally white (or any other unusual colour) is dependent on the amount of pigmentation shift. Most birds that have variable colouration only have slight variations from their normal plumage colours with the unusual-coloured feathers generally appearing around the neck or back; this sort of variation is not uncommon. The sudden appearance of a bird (or birds) with a few white feathers normally means that new birds have appeared in the area, rather than the existing birds suddenly changing colour.

In other ‘black’ birds such as the introduced European Blackbird there is a tendency for partially albinistic birds to appear in late winter or early spring.  This coincides with their moulting pattern.  Perhaps it is the same with crows and ravens.

Comments (4)

sort by
newest
oldest
Margot 17 June, 2009 09:58
How is blue created in bird feathers please
reply
Discovery Centre 25 June, 2009 15:38

Thanks for your interesting question, Margot. We'll check with one of our bird experts and get back to you soon with a response!

close this reply
Write your reply to Discovery Centre's comment All fields are required

We love receiving comments, but can’t always respond.

Kate 28 October, 2012 10:54
There is a young magpie in Evans Head NSW which is brown and white rather than black and white. It is so unusual many people think it is a cuckoo that hatched in the magpie nest but morphologically it is definitely a magpie and the pattern of brown(buff) and white is the same as on the other normal babies? Why is this baby so different and will it stay that way as it grows up?
reply
Discovery Centre 29 October, 2012 11:37

Hello again Kate

We ran this past the experts in our Ornithology Department, and they have responded to your query as follows:

The black colour in magpies and other birds is due to melanin pigments deposited in the feathers. There are two types of melanins, called “eumelanins” and “phaeomelanins”. The former produces greys and black, the latter produces varying shades of brown and chestnut. What color you see depends on how much of each type of melanin is present. More eumelanin, you get grey or black. More phaeomelanin, you get brown or chestnut. If you have neither, you would get white feathers.

What may be happening is that there is some genetic mutation that is preventing eumelanin production. If the phaeomelanin is still produced, however, you would get brown feathers, rather than white (what’s known as leucism).

Also, the occurrence of this colour mutation is higher in NE NSW and SE Qld for some unknown reason.  Up there this colour also commonly occurs in the Torresian Crow and could account for misidentification of this species as the Asian House Crow. This is a rare type of plumage aberration, but not as rare as albinism.

Hope this helps!