[Tweeters] Gynandromorph Mallard in the Carkeek Wetlands Saturday morning

[Matt Dufort]

Hi Nathaniel and Tweeters,

This intersex Mallard is a really neat bird.  There are a handful of
reports of one at Carkeek over the last two months, which I assume is the
same individual.  I have photos from January 8 that I haven't yet added to
eBird, that look very similar to those posted by Thomas Gergen.  And Sarah
Peden's photos here also look like the same bird:
https://ebird.org/checklist/S129040845.

I did some reading on such birds when I saw this one earlier this winter.
The prevailing theory is that this is typically caused by female birds
losing the function of their single ovary, and thus losing production of
female sex hormones.  When this happens, the other gonad often develops and
starts producing male sex hormones, which cause the bird to develop male
traits.  It's been studied most extensively in chickens.  If you want to
learn more about this, I'd recommend this review:
https://www.karger.com/Article/FullText/448365.

Good birding,
Matt Dufort

On Sat, Mar 4, 2023 at 8:51 PM Nathaniel Peters <ncpeters at uw.edu> wrote:


> Howdy Tweets!

>

> The monthly Carkeek Park Neighborhood Bird Outing that I lead for Seattle

> Audubon had fantastic luck today in the chilly wet weather, when we pretty

> much had the park to ourselves.

>

> One of the big highlights of the trip was discovering what I believe to be

> a gynandromorph/intersex Mallard in the wetlands around 10:15AM.  We were

> on the boardwalk looking at the 40-50 Mallards there, when I noticed a very

> unusual individual.  This Mallard had the crown, breast, wings, and curl

> feathers of a male Mallard with the cheeks, flanks, and tail of a female

> Mallard.  The bill was very dark at the base and had a yellow/orange tip.

> I received confirmation from Dennis Paulson that this bird looks good for a

> gynandromorph, and I am fairly confident on my call.  I also welcome the

> thoughts of others if anyone else is able to locate the bird.

>

> I have some decent quality iPhone pictures and am in the process of

> collecting more from my walk participants.  I went back at around 330pm but

> all the ducks were gone at that time.  I will probably try again tomorrow

> morning and see if I can relocate the bird.  If anyone would me to send

> them the pictures, let me know.

>

> Happy birding!

>

> Nathaniel Peters

> Seattle, WA

> --

> -

> May the* F*lu*OR*escen*CE* be with you!

> -

> Nathaniel Peters Ph.D.

> W. M. Keck Microscopy Center Manager

> University of Washington

> ncpeters at uw.edu

>

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