About us: We own the Wild Birds Unlimited nature shop in East Lansing, Michigan,
a store that provides a wide variety of supplies to help you enjoy the birdwatching hobby.

This blog was created to answer frequently asked questions & to share nature stories and photographs.
To contribute, email me at bloubird@gmail.com.

Friday, January 23, 2009

Photo Share: Leucism in birds

I was reading the blog about the snow bunting and I have my own interesting bird photo to share. Last February what looked to be a female sparrow with strangely light plumage was at one of my feeders along with a bunch of house sparrows. Is this a different species or simply an odd color mutation?~ Lansing, MI


It is a house sparrow with leucism. Right now scientist describe two kinds of Leucistic birds, pale and pied. Pale leucistic birds, like the one in your photo, will have the same markings, but extremely pale.

Pied Leucistic birds have patches of white. Leucistic birds are relatively unusual but much more common than albino birds which are completely white with pink eyes, legs and bill.

The terms leucistic and leucism are derived from medical terminology. The prefix leuc- is the Latin variant of leuk- from the Greek leukos meaning "white". The correct pronunciation of leucistic is ( loo-kiss-tic) and leucism is (loo-kism) since the prefix in Greek and Latin are pronounced with the hard C or K sound.

This bird was very popular at the feeders in your area. I received several photos last year of this little streaker. Thank you for sharing.

2 comments:

Anonymous said...

Ive got one of them in West BRanch.

Christopher Gordon said...

I came to this post because I saw a pale Passer domesticus today while walking back to my home in New Brunswick, NJ. The bird was a female, like the two pics you shared here. You describe the term "leucism" which is really just a general term for "melanin reduction", as opposed to albinism, which is "inability to produce melanin." Basically, albinos are white and lecistics are paler-than-normal to some degree, but still show that melanin is produced. Among many species of cage-birds, there are a few "leucistic" mutations which are known and differ both in phenotype and inheritance. I'm guessing that what we're seeing is what is known as "Cinnamon" in the US and mostly among psittacines, or "Isabelle" in Europe and mostly among finches. Under either name, the mutation is a sex-linked recessive, being passed-on via the Z chromosome. Male birds are ZZ, females are ZW (in mammals, males are XY and females are XX, an opposite arrangement). So female Cinnamon/Isabelle birds need to inherit only one copy of a sex-linked mutant gene -- from their heterozygous "normal-looking" fathers. This would mean that while Cinnamon/Isabelle House Sparrows are very rare in the wild, most of them are female. For a male to be Cinnamon/Isabelle, he'd need a Cinnamon/Isabelle mother who mated with a male which was heterozygous for the mutation (or, of course, from two Cinnamon/Isabelle parents, which would be even less-likely in the wild).