Outdoor Ontario

Discussion => General Discussions => Topic started by: Napper on December 13, 2007, 06:30:07 PM

Title: Albino Crows
Post by: Napper on December 13, 2007, 06:30:07 PM

Albino Crows

First of all it doesn't seem to  be a scientific term.. Is there a correct  term for this?

I found this link below "Ont Birds"  just two weeks ago and this is where the story starts.

http://www.greatblue.com/bmail/ontbirds ... dex.html#6 (http://www.greatblue.com/bmail/ontbirds/200712/04/index.html#6)


 Just the other day as I was looking thru some old images,  I was hoping to find something I could practice and learn some Photoshop stuff on.  I found  one

with two Crows and a Coopers hawk.. It looked a little strange so I looked a little closer and was surprised to see what appeared to be two partial Albino

Crows..

Anybody?  .. Napper :?   oops that was fast"Partial amelanism or Amelanistic"


 (http://outdoorontario.net/Gallery/albums/album11/crowsand_coopers1.jpg)
(http://outdoorontario.net/Gallery/albums/album11/crowsand_coopers3.jpg)
(http://outdoorontario.net/Gallery/albums/album11/crowsand_coopers2.jpg)  


"If I find the correct term I will edit this post.."

Title:
Post by: Kin Lau on December 13, 2007, 07:27:33 PM

Ah... Crow, the other white meat :)

I got a call from a friend in Cornwall a couple of weeks ago, that they have an "amelanistc" crow as well, very similar to the one in Niagara.

Title: Leucism?
Post by: Brian Bailey on December 13, 2007, 11:25:00 PM

"Amelanistic" is a new one to me.  I guess it makes sense:  the opposite of melanistic, but I think the more widely used term is "leucistic".  

I'm no expert, but a Google search will pull up lots of information on leucism.  

BB

Title:
Post by: Pat Hodgson on December 14, 2007, 02:57:05 PM

The ABA's magazine "Birding" of Sept/Oct 2007 had a very nice article called "Color Abnormalities in Birds - A Proposed Nomenclature for Birders".  There has been confusion and misuse of terminology.  They propose some logical standardization, focusing on the biological mechanism behind the observed abnormalities.

Following this article, these crows, with light patches but still with plenty of normal black, have "partial amelanism".  Partial as in only on part of the body - total amelanism means no melanin anywhere, and hypomelanism means reduced levels resulting in faded appearance all over.    It goes on to get even more complicated as there are different types of melanin, too, mainly types that make black and types that makes brown.

I liked the article and it seemed logical but I'm not sure it will be widely read enough to "take" with the public.  The authors don't like the use of either albinism or leucism, because these terms are poorly defined (have very broad meanings) and do not account for the mechanism involved.

Title:
Post by: Pat Hodgson on December 14, 2007, 03:16:48 PM

actually, are you sure this is not just a trick of the light?
sometimes black can sort of reflect into a sheer gray
I'm just suspicious because the gray is sort of in the same place on the birds and could be due to light
also as you say you were looking through old photos, not seeing them live recently

Title: trick of light
Post by: Napper on December 14, 2007, 06:07:46 PM

Hi

I thought that as well.. I am facing the escarpment  that is Kelso point  in the background. Derry rd is visible through the trees and I am say, 500 metres East of

hwy 25..  the data on the image says Feb 11, 2007 15:33 pm. I am no xpert but I think am facing nearly due West.

I also thought it was a large leaf in front of the lower Crow but there are no leaves on any of the trees.. It mignt be a damaged image.. I have a backup of

everything I will try to find it again.. I dunno :?

My second backup shows the same whitish on the lower crow..

Title:
Post by: Brian Bailey on December 14, 2007, 11:00:24 PM

Hmm...
At first I thought the whitish part was maybe something stuck in that small branch, but I think that branch has to be on the other side of the bird, so that can't be.  The pattern of the pale parts is consistent with it being whitish coverts and primaries of the left wing.  There's a slight bit of grey on the head that could well be a lighting effect, but it appears to be an overcast day, so I doubt there would be any big patches of strong light reflection.

As for what to call the condition, from my small amount of research, I still like "Leucism".  It is a general term for a lack of colour pigment.  Clearly, a crow with a white wing is lacking some pigment.  I'm not a biologist, so I don't know which pigment is absent (although melanin seems like a pretty good guess).  

I know there are a variety of other pigment abnormalities with specific names as well.  I have seen House Finches and Rose-breasted Grosbeaks that have yellow in place of the red.  That condition has a name too, but I probably couldn't pronounce it even if I could remember it.

BB

Title:
Post by: Pat Hodgson on December 15, 2007, 08:34:28 AM

the same article refers to any abnormalities in the yellow/orange/red colours as carotenism

if you want to get into really weird abnormalities, search for "bilateral gynandromorph"