Albinism and Leucism. When is a bird an albino? When is it leucistic?
What is albinism? What is leucism? From Merriam-Webster Dictionary:
Albinism – exhibiting the traits of an albino.
Albino – any creature who is congenitally (from birth) deficient in pigment and usually has a milky or translucent skin; white or colorless hair, fur, or feathers; and eyes with a pink or blue iris with a deep red pupil.
Leucism – an abnormal condition of reduced pigmentation affecting various animals (such as birds, mammals, and reptiles) that is marked by an overall pale color or patches of reduced coloring, and is caused by a genetic mutation which inhibits melanin and other pigments from being deposited in feathers, hair, or skin.
Melanin – any of various black, brown, reddish-brown, reddish-yellow, or yellow pigments …… that are found especially in skin, hair, feathers, and eyes.
I have never seen an albino bird – they are rare. But, some of my birding friends have, and I have seen photos. I think the key to determine whether or not a bird is an albino, or has the condition called leucism, is to look at the eye. Is it red or pink? If the bird you are looking at has a red or pink eye, it is an albino. If the eye is the color of all the other birds of the species – and not pink or red – then you are not seeing an albino bird, but something else. And a condition to consider is leucism.
For example, an American Robin has a gray head, back, folded wings, and tail. It has an orangish-red breast and dark eyes. If a robin is an albino, it will have all white feathers and the eye will be pink or red. If a robin is leucistic, some, or all, of its feathers will be pale or white, but the eye will be dark. A Common Grackle is iridescent black and dark brown. Its eye will be yellow with a dark center. An albino Common Grackle will have white feathers and a pink or red eye. If this grackle is leucistic, some, or all, of its feathers will be pale or white, but the eye will still be yellow with a dark center. Leucism does not affect eye color; albinism does.
I think leucism is more common than albinism, and I base that on the fact that I have seen House Finches and robins who exhibit the traits, but never an albino in either species. A leucistic bird will show patches of white feathers – sometimes only one or two feathers, sometimes whole areas of a bird, and sometimes the entire bird. If it is patches or areas, these can be scattered all over the body. What my birding friends and I have noticed is that in our experience, it seems to be more common in House Finches. House Finches are often in small flocks – especially at feeders in fall and winter. This is where you might see an odd-looking bird that in silhouette, size, shape of beak, and behavior is a House Finch, but the feathers are all wrong. They are mottled with white or look almost colorless, or the entire bird is white or pale. If you observe anything like what I have described, the bird you are observing is most likely leucistic. Make sure you get a good look at the eye to help confirm this. Leucism does not affect the health of the bird at all – just its appearance.
As to a bird being an albino – this condition is dangerous for them. Feathers serve as camouflage. Songbirds are prey. Unless it is a snowy day, or the bird is on a sandy beach or within sandy dunes, a bird that is all white stands out.
That is why on songbirds, white (or any pale colors like pale gray, cream, or buff) is generally on the lower breast or throat. When the bird is on the ground or perched on a branch, its body or beak hides the white from anything overhead. And the white on wing-bars is just a small line, so not prominent or too obvious. And sad to say but there are people who will kill any albino animal as a trophy. It is my guess that any bird – or creature – who is an albino will not live long.
You can be a birder of many years, or for your whole life, and never see either of these conditions. But keep both in mind – especially if you see an odd, whitish or rather colorless bird in front of you, and your immediate reaction is, “What in the world……… ??????”