Odd duck- mallardlike male without breeding plumage in Leipzig, Germany this march (1 Viewer)

[Joern Lehmhus]

https://flic.kr/p/2pQT9iU

found by Micarusa and sent to me for identification help....

Micarusa informed me that this mallard-sized bird displayed as a male mallard, in a group with typically colored male mallards. It did the grunt-whistle, for example...
I first considered an intersex plumaged female, but with that behaviour this doesn´t seem likely. As far as i know, when showing male display behaviour , the duck in question should be male...

It also doesn´t match any of those mallard-like species with no developed breeding plumage, like Hawaiian duck, Pacific Black duck, Mottled duck, Mexican duck, American black duck or Laysan duck. It also doesn´t match first generation crosses of Mallard with any of these species...

So we do not know what to think here...
Maybe somebody else has encountered something similar or has an idea???

 

[Butty]

I see duck-things pretty simplistically so I may be missing a point - but... Why isn't it just some unremarkable (non-)selectively-bred domestic (mallard) duck?

 

[Joern Lehmhus]

What sex then?

As far as I know there is no possibility for a breeding plumage male domestic duck to show that much female type plumage . Yes, there are breeds where male and female look more similar than in wild mallard, but these have plumages highly deviating from wild type mallards.

This here is close to wild type but showing male and female traits ,
somewhat similar to that what you see in hybrids of mallard with the related species that wear no distinct male breeding plumage...

 

[Joern Lehmhus]

This would be examples for domestic mallard breeds where male and female are more alike:

https://www.dunlaphatcherypoultry.com/wp-content/uploads/2020/01/BLUE-SWEDISH-PAIR.jpg

https://m.media-amazon.com/images/I/71yzLgL5f-L._AC_UF894,1000_QL80_.jpg

https://blog.meyerhatchery.com/wp-content/uploads/2022/02/Khaki-Campbell-Blog-3-1.png

These would be some examples for hybrids of mallard with species that are closely related to mallard but have no distinct breeding plumage

mallard x hawaiian duck

https://inaturalist-open-data.s3.amazonaws.com/photos/12363545/large.jpg

mallard x mexican duck

Mallard x Mexican Duck

Mallard x Mexican Duck hybrid, Pena Blanca Lake, Santa Rita County (Arizona, USA), 20th January 2015 - copyright Steve Mlodinow (photo ...

birdhybrids.blogspot.com

mallard x pacific black duck

https://cdn.download.ams.birds.cornell.edu/api/v1/asset/233291341/480

https://epistemiccuriosity.blog/wp-content/uploads/2022/03/anas-superciliosa-c397-platyrhynchos-14-geoffrey-cox-cc-by.jpeg

mallard x spotbill (Eastern and Indian)

Mallard x Indian Spot-billed Duck

captive Mallard x Indian Spot-billed Duck hybrid, Blakeney Collection (Norfolk, UK), 22nd February 2014 - copyright Dave Appleton (phot...

birdhybrids.blogspot.com

https://www.zoochat.com/community/media/spot-billed-duck-x-mallard-hybrid-arisugawa-park.707563/full?d=1707740304

https://cdn.download.ams.birds.cornell.edu/api/v1/asset/614297757/1200

 

[Southern Viking]

Do intersex birds only occur in females Joern? Intersex male would seem the logical answer, but I guess there's a reason you haven't suggested that?

 

[Joern Lehmhus]

The intersex plumage in females seems to be in general due to hormonal issues. If female birds are low in estrogenes due to very old age or some pathological issue as for example ovary cancer, they tend to develop male plumage characteristics. This has been found for single individuals of different duck and pheasant species with this characteristic that have been checked with blood samples or dissected after death, as far as i remember.

So as i do not know any case of a male bird with intersex plumage, I do not know if they exist. Therefore I am not sure if this condition can be caused in male birds the same way-- with excess estrogenes perhaps?

However, there are also these mallard relatives I mentioned before, where the males do not habve this distinctly different breeding plumage . How did that develop? Just spculating: If that was a muation in a single gene , it may be happening again in mallard individuals. Speaking against this single gene theory is that there are so many different variants in hybrids and backcrosses of mallard hybrids with those species without a distinct breeding plumage ... I think it can´t just be a single gene.

example: some birds with mallard x American black duck mixed ancestry (probably not all first generation hybrids)

American Black Duck x Mallard

American Black Duck x Mallard hybrid, Ottawa River, Ottawa (Ontario, Canada), 7th April 2016 - copyright Gordon Johnston (photo ID: 278...

birdhybrids.blogspot.com

https://flic.kr/p/7TwTtE

https://flic.kr/p/FpQQKK

https://flic.kr/p/rjQA6i

https://flic.kr/p/dSyTY8

 

[Joern Lehmhus]

https://flic.kr/p/9rpWQr

https://flic.kr/p/9FcKBH

https://flic.kr/p/CSqiP8

https://flic.kr/p/68yzJC

huge variability , you can find a gradual change from nearly mallardlike birds to nearly black duck like birds...

 

[Joern Lehmhus]

And it is the same variability in for example, mallard x koloa, mallard x pacific black duck etc. .. so I think probably not a single gene involved, but some more...

 

[dantheman]

And it is the same variability in for example, mallard x koloa, mallard x pacific black duck etc. .. so I think probably not a single gene involved, but some more...

I had a moment there - is that where the duck-billed platypus came from?

;-)