[Tweeters] Leucism vs. albinism

Hans-Joachim Feddern thefedderns at gmail.com
Sat Mar 7 15:52:42 PST 2009


This discussion brings to mind the albino (?) YELLOW-BILLED LOON which
wintered in the lower Puget Sound for 6 to 7 - or more winters. I was
able to observe it closely in late April and into early May from the
Dash Point Dock. It had molted into breeding plumage, meaning that on
close range, one could see all the loon markings, such as neck rings,
pearly back etc. The difference was though, all markings were light
brown to orange, much like a "paint by the numbers'' scheme, except
that Mother Nature did not get a chance to fill in the colors! This
bird obviously was able to survive in the Arctic for many years. I
often wondered, if it would pair off with a normally colored Loon and
was able to breed successfully. It has not been seen for a couple of
years and is probably gon now. It was always like seeing an old friend
again every fall! I always wished to ask it, how and where it spend
it's summer!

Hans Feddern
Twin Lakes - Federal Way, WA.

On 3/7/09, Doug Schonewald <dschone8 at donobi.net> wrote:

> Tweets,

>

> This is an interesting topic. Actually I believe there are very, very few

> truly albinistic birds, and those seldom survive to adulthood, based on some

> past research. Almost every bird that you see with white feathers is

> leucistic, partially leucistic, or one of a number of other genetic

> disorders such as Dilution, Ino, Schizochroism, etc. All are genetically

> generated, but differ from albinism in that the coloring agents (eumelanin

> and phaeomelanin) are present, but are either not transferred to the

> feather or are present in lower amounts which creates diluted plumage

> colorations. An excellent treatise on the subject can be found at:

>

> http://www.vogelringschier.nl/DB28(2)79-89_2006.pdf

>

> The paper was written by Hein van Grouw, longtime curator of the Natural

> Museum of History - Netherlands in 2006 and is written in a way that us

> common folks can understand most of it.

>

> To be fair, a contrary paper using the terminology of albinism to describe

> all white occurrences in plumage is:

>

> http://elibrary.unm.edu/sora/JFO/v036n02/p0067-p0071.pdf

>

> While Mr. Gross wrote this paper in 1965, most of his citations were from

> the late 1800's with a couple from 1928 and 1957. I find his paper less

> convincing since we have learned so much since then. Once thing in this

> paper that is fascinating is the list of birds and bird families and the

> occurrence of white in the feathering in each. Very good information, even

> if it is slightly dated.

>

> As far as terminology, I don't think it really matters. The terms albino,

> partial albino, leucistic, and partial leucism have been used

> interchangeably for years by both researchers and lay birders, and it

> unlikely that it will change. However, understanding the processes at work

> will help us better understand how and why birds sometimes look like they

> do.

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