[Tweeters] Rare Café-colored Crow pigment mutation near Seward Park 1.21.2019

Devorah the Ornithologist birdologist at gmail.com
Tue Jan 22 02:07:58 PST 2019


Those are absolutely gorgeous photos, Joshua.

To answer a few questions: the colour morph of that particular crow is
known as "cinnamon" in the avicultural world (which is mostly about
captive-breeding parrots, songbirds and waterfowl). although cinnamon
morphs look more-or-less the same, the genetics underlying this colour
mutation affect the colour, size or shape of melanin granules, which give
the birds their distinctive plumage colours. Thus, "cinnamon" is a generic
sort of term that describes the bird's visible colour rather than the
precise genetics that give rise to it.

Let me explain: there are two forms of melanin produced by birds:
pheomelanin, which is reddish to yellowish in colour; and eumelanin, which
is dark brown to black. Thus, the cinnamon colour morph can result from a
mutation in a number of genes within the melanin production pathway, and
these mutations can differ between individuals whose colouring appears "the
same". Further, some cinnamon morphs result from an autosomal dominant gene
mutation (so the bird needs only a single copy of the relevant gene
mutation to create this colour morph), whereas other cinnamon colour morphs
are produced by a recessive gene mutation (which means that the bird needs
two copies -- identical copies? perhaps, but perhaps not -- of the relevant
gene mutation to make the colour visible.) Nevertheless, regardless of the
genetics that underlie this particular crow's colour morph, which step(s)
in the melanin production pathway that are affected, and which type of
melanin molecule is affected, and how it is altered, the result in this
particular crow is that melanins are not properly produced, which gives the
affected bird its distinctive colour. As an aside, at least one mutation
that gives rise to a genetically dominant cinnamon colour morph is a
semi-dominant lethal mutation (meaning that the unfortunate bird who ends
up with two copies of this dominant gene will die, either in the egg or as
a nestling.) Based on this, one can conclude that such a colour morph
affects metabolic or developmental pathways that are essential to life.

To my eyes, Trileigh's "brown" crow looks different from Joshua's cinnamon
crow. It could be differences in lighting, but it appears to me that
Joshua's cinnamon crow has dark legs and a dark beak, whereas Trileigh's
"brown" crow is all brown -- even the legs and beak (which appears to have
a pale horn-coloured tip). Do they share a mutation or two? It's difficult
to say, but Trileigh's "brown" crow could also result from a fallow
mutation, which is recessive, and also affects eye colour (unlike any of
the "cinnamon" mutations), making the eye paler than normal, or even red in
colour. (Keeping in mind that there are other gene mutations that affect
ONLY eye colour, but not plumage colour, and therefore are not considered
to be fallow morph mutations.)

leucistic birds lack the ability to produce any melanin at all, either in
some or all of their feathers, so their feathers are white.

hope this helps.


On Tue, Jan 22, 2019 at 1:52 AM kelsberg <kelsberg at uw.edu> wrote:


> Thanks! Glad you took nice photos.

> Gary

>

> On Jan 21, 2019, at 3:12 PM, Joshua Glant <josh.n.glant at gmail.com> wrote:

>

> That blond crow at Seward Park has been there for at least a year! I took

> photos of it last winter:

>

> https://flickr.com/photos/132642556@N03/sets/72157666255642248

>

> Good birding, Joshua Glant

>

> On Jan 21, 2019, at 1:15 PM, Tucker, Trileigh <TRI at seattleu.edu> wrote:

>

> Hi Tweets,

>

> That’s a beautiful bird, Gary! It reminds me of a brown crow I’ve seen in

> Lincoln Park (West Seattle) - photos here

> <https://www.flickr.com/search/?user_id=37263485%40N03&view_all=1&text=brown%20crow>.

> Although my local one doesn’t have the dramatic coloring of Gary’s, I

> wonder if there might be some shared genetic modifications.

>

> Good birding to all,

> Trileigh

> (About to head for Tanzania, woohoo!)

>

> *~ ~ ~ ~ ~ ~ ~ ~ ~ ~*

> *Trileigh Tucker, PhD*

> *Professor Emerita of Environmental Studies, **Seattle University*

> *Pelly Valley, West Seattle*

> *Natural Presence Arts website <https://naturalpresencearts.com/>*

> *Photography

> <https://www.flickr.com/photos/trileigh/albums/72157661836833455>*

>

> From: kelsberg <kelsberg at uw.edu>

> Date: Monday, January 21, 2019 at 11:52 AM

> To: "tweeters at u.washington.edu" <tweeters at u.washington.edu>

> Subject: [Tweeters] Rare Café-colored Crow pigment mutation near Seward

> Park 1.21.2019

>

> I saw an unusually pigmented crow (I've never seen anything like it

> before) this morning from the pedestrian path along Lake Washington Blvd,

> about 1/2 mile north of Seward Park. Overall, it was café-au-lait, with a

> darker brown head and proximal tail, medium brown over the back and much of

> the wings, and white wing tips and distal tail and flight feathers.

>

>

> It was foraging on the lawn near where some picnic must have happened,

> since it took flight with what appeared to be a piece of watermelon.

>

>

> I took a quick burst of iPhone photos (low quality), which I've posted on

> the public Flickr account at:

> https://www.flickr.com/photos/145727674@N05/?

>

>

> If they are not visible I can also email them to anyone who is interested.

>

>

> I sent some of the photos to Dennis Paulson, who said he'd never seen one

> like it either and suggested that it was a rare mutation. He hoped some

> photographers might track it down and get better images.

>

>

> Good hunting!

>

>

> Gary Kelsberg

>

> Seattle

>

>

> kelsberg at u dot washington dot edu

>

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