Just one last (hopefully) note.

Birds grow feathers in tracts along their bodies. If you take a look at a
nestling just starting to grow the feathers, most of the skin complete lacks
feather follicles. The feathers grow in a few areas, such as along the
spine, all over the head and over most of the wing. There is a dorsal tract
but I can't remember where exactly (and my references are in a different
room). The main point is a small injury in the right place would result in
a fairly large white spot. A large injury in the areas without feathers
wouldn't cause any white spots.

The head is another matter. Kelly McAllister's robin (mostly white head and
some white primaries) sounds more like a genetic/developmental thing to me
because it affects two different feather tracts.

Thanks for all the information.
Deb

Deb Beutler
Dept. of Zoology
Washington State University
Pullman, Whitman Co., WA

dbeutler at wsunix.wsu.edu
-----Original Message-----
From: tuisto at oz.net <tuisto at oz.net>
To: Herb Curl <herb_curl at hazmat.noaa.gov>; tweeters at u.washington.edu
<tweeters at u.washington.edu>
Date: Tuesday, January 26, 1999 2:18 AM
Subject: Re: Pigments and albinism


>At 11:27 AM 1/23/99 -0800, Herb Curl wrote:
>
>>I received a 2nd degree (blistering) sunburn on my arm
>>while mountain climbing, having missed an area with sunscreen.
>>Subsequently that area became depigmented and will no longer tan.
>
>Deb Beutler wrote:
>
>> I have a large patch of white skin on my arm
>where I burned it. When you freeze-brand a bison, the hair grows over the
>brand but the hair is white. Couldn't the same thing happen in birds?
<snip>
>My sister's dog has a ring of white hair around his black muzzle from the
>string his first master used to tied his mouth shut. He has had it since
he
>was six months old.
>
>Paul Talbert wrote:
>
>>If I actually did see a robin with a white spot on its back, I would be
>>less eager to invoke a pied mutation because the back is an unlikely
place
>>for this kind of white patch.
>
>And Deb Beutler replied:
>
>>I have seen one like that. While I was assisting a bander in southern
>Idaho, we banded a robin with a large patch of white feathers on her back.
>
>And Kelly McAllister wrote:
>
>> I saw that it was a pied robin. Its head was mostly white.
>It had white primaries on both wings and a few stray white blotches
>elsewhere, like on the back.
>
>
>Thanks for all these interesting observations. I guess I'm convinced that
>pigment loss from injuries is more common than I thought, especially from
>burns. I still think that you should be able to make an educated guess
>about many cases of partial pigment loss by the distribution of depigmented
>areas. Symmetrical placement is almost surely a pattern mutation. Deb's
>robin is not typical for a spotting (pied) mutation and injury seems as
>reasonable a cause as any. Kelly's robin, on the other hand seems like it
>could be a spotting mutation even though it had blotches on the back. The
>white primaries are appropriately distant from the spinal cord. The "mostly
>white" head probably also includes ventral areas, and it is hard to imagine
>that a robin could sustain serious injury to most of its head and survive
>without an excellent insurance plan.
> I checked the Seward park mutant mallards again, and their (ventral) white
>breast spots are not symmetrical and do not coincide with the brown patch
>on the normal mallards, so I do not think they have a pattern element
>mutation. A spotting mutation seems likely. I am actually more interested
>in why they are overall more brown than the normal mallards.
> The predominantly ventral white patches that are typical of many spotting
>mutations result from failure of the pigment cells to migrate completely,
>but I think I recall that there are other spotting mutations that simply
>cause some of the pigment cells to die off at random. The spots caused by
>these mutations would not necessarily be predominantly ventral. As an
>aside, many of these spotting mutations have serious effects on other
>tissues as well. For example, deafness in white cats and Dalmatians (dogs,
>not humans) occurs because pigment cells are necessary for the proper
>differentiation of the inner ear.
>
>Carotenoids:
> Besides the consumption of massive quantities of orange juice and carrots,
>there are other ways to get carotenoids in your skin. When I was younger
>and had a more adventurous fashion sense, and punk hair colors did not yet
>exist, I tried applying henna to my hair to see what life was like as a
>redhead. I learned that henna is more effective at turning scalp orange
>than at turning hair red. On someone who began exhibitng male pattern
>baldness at the tender age of 14, it made for an interesting effect.
>
>
>Paul Talbert
>tuisto at oz.net
>