Odd duck at Fort Collins City Park (Sheldon Lake)

DAVID A LEATHERMAN

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Dec 6, 2020, 12:21:38 AM12/6/20

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Today at Sheldon Lake in Fort Collins City Park I was scanning thru the 150 or so Mallards and saw one with a head that was green throughout the top half and tan throughout the bottom half. It had a maroon chest, yellow and black beak and body like a female Mallard. In perusing the Sibley Field Guide he actually shows a very similar bird and says it is a known rare occurrence of a female that has certain male field marks (namely, the top of the head coloration and the chest). I have seen individuals that apparently are hybrids between Mallard and Black or Mallard and Mexican, that show odd green color configurations on the head, but never one with this head pattern and assortment of other gender characteristics. Just thought I'd share.

Dave Leatherman

Fort Collins

Sebastian Patti

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Dec 6, 2020, 8:21:57 AM12/6/20

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Age may play a role in that as well . . . possibly a VERY old female.

sebasti...@hotmail.com
Sebastian T. Patti
770 S. Grand Avenue

Unit 3088

Los Angeles, CA 90017
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From: cob...@googlegroups.com <cob...@googlegroups.com> on behalf of DAVID A LEATHERMAN <daleat...@msn.com>
Sent: Saturday, December 5, 2020 11:21 PM
To: Colorado Birds <cob...@googlegroups.com>
Subject: [cobirds] Odd duck at Fort Collins City Park (Sheldon Lake) - Larimer on 5Dec2020

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Kathy and Jeff Dunning

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Dec 6, 2020, 9:42:23 AM12/6/20

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I agree with Sebastian.

I had a very similar creature a couple of summers ago in the mountains and sent the photos to Steve Mlodinow. He responded that it was likely an "intersex duck". This occurs when a female gets old, starts running low on hormones and starts looking like a basic plumaged (ie: breeding plumage) male.

Pretty cool.

Good birding,
Kathy Mihm Dunning

Denver

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Eric DeFonso

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Dec 6, 2020, 11:12:58 AM12/6/20

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The following link goes to an article on the BBC page from a few years ago, titled, "How Does a Duck Change Its Sex?" It does a nice job explaining in layperson terms of genetics and life history what the phenomenon even is, and although it's mostly about the article writer's particular Mandarin Duck, it applies to most if not all ducks.

A very pertinent and recommended read:

https://www.bbc.com/news/science-environment-40016817

Eric

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Eric DeFonso
near Lyons, Boulder County, CO

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DAVID A LEATHERMAN

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Dec 6, 2020, 12:18:04 PM12/6/20

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I received several responses to my post about the odd Mallard with a mix of female and male characteristics. All but one suggest this emergence of male field marks can happen to very old females. Eric DeFonso astutely sent the message below which contains a link to an article that might be a very good explanation of this phenomenon. I thank everyone who responded.

Learning something new so early in the day takes the pressure off the rest of it, and now I can just watch the NFL (another example of a once robust sport species that has lost many of its former characteristics (long pass plays, quarterbacks who last an entire season, games not dominated by official reviews, screaming fans, etc).

Dave Leatherman

Fort Collins