Help w/ weird duck - Merced NWR, California (1 Viewer)

[mojoedevine]

A birder submitted the attached photo of a male N. Pintail at Merced NWR, Ca this last week (4-16-21). I'm not good w/ hybrid ducks or aberrant plumages, so I'm asking for your help. The sides & a portion of the hip patch show strong light & dark brown barring; not the typical gray of an adult male. It my be an aberrant N. Pintail but the brown coloration of the sides don't seem possible. Am I wrong about that? If it's a hybrid, the only other ducks that I can find in Sibley's that shows this barred pattern on the sides & thru the hip patch are 2 of the eiders. The potential of a hybrid involving another species of duck such as Blue-winged Teal or a Cackling Goose (I'm grasping at straws here) seem unlikely to me as both of those have strong white hip patches w/out the barring this duck shows. Help please. Thanks.

Joe Devine
Merced County, California, US

 

[Butty]

Looks like a (normal) eclipse male northern pintail. So I expect its moult schedule just got a bit mucked up.
I'm guessing where 'Ca' is.

 

[nartreb]

The "grey" flanks of a northern pintail in fact are always finely vermiculated or zebra-striped. Eclipse or immature ducks have obvious brownish stripes, and pale heads. I'm wondering if your bird hasn't quite completed its molt -- somebody will come along in a minute and tell us if that's at all likely. Or maybe it's just fluffing its flank feathers in an unusual way - note the position of the wing - that makes the stripes look bigger than usual. (And then we'd have to blame strong light for the pale head... I'm not 100% convinced about that.)

In short, I'm no expert in pintails, but I'm not ready to reach for the H-word yet.

 

[mojoedevine]

Sorry all - California, US

 

[Joern Lehmhus]

could also be an intersex bird - that zebra flank pattern is also common in intersex plumaged pintails

https://flic.kr/p/jXHpCa

https://flic.kr/p/b1uvHp

https://flic.kr/p/nTnWzJ

 

[Butty]

could also be an intersex bird

How would one distinguish between an intersex bird and a normal male that's moulting unusually early/late?

 

[Joern Lehmhus]

as pintail intersex pattern is as variable as in mallard that is not always easy , but flank barring in intersexes seems more pronounced and intersexes have a more capped head pattern. ofter there is also more black on the bill than in eclipse males

 

[Butty]

So how is it known that these birds are intersex rather than being normal males with plumage at the extremes of variation?

 

[Joern Lehmhus]

The last photo is an old female from Hagenbeck zoo Hamburg;
and then there is 2 publications on two such birds (from Japan, I seem to remember, have saved it somewhere) which were dissected after their death and found to be females with anomalies in the ovaries, in one case I think it was a cancer tumor

therefore I assume it is the same with similar plumaged birds.

It is easier in mallards because the intersex birds show iridescent green on the head, so here with pintail without marked irirdescence, one clue is lost

 

[mojoedevine]

Joern,

I did a little more searching on the web for pics & your explanation fits what I found. I hadn't heard the term intersex before but it's similar to the term in this paper - females w/ masculinized plumage. The researchers did a necropsy on 8 N. Pintail individuals & found them all female. I also read that several duck species throw these anomalous plumages. They're infertile & the percentage is said to be less than 0.1% of the population. Again, thanks for the input. Helped me track down this paper.

A study on the Northern Pintail (Anas acuta) females with masculinized plumage: their prevalence, morphological and behavioral traits, and reproductive organs | Semantic Scholar

It is considered that all of these masculinized traits seen in the Northern Pintail females were caused by spontaneous ovarian degeneration after sex differentiation. We report here on the prevalence, morphological and behavioral traits, and gonadal condition of anomalous Northern Pintail (Anas...

www.semanticscholar.org

 

[Joern Lehmhus]

yeah, thats one of the papers, forgot that they had more than one bird though...


As an addition : that is what an intersex Common or Greenwinged teal looks (also with flank barring)

https://pbs.twimg.com/media/ETgX8EvWoAAPT0P?format=jpg&name=900x900

https://4.bp.blogspot.com/-wiJ6j8XsmUE/WLXBu0sDE7I/AAAAAAAAS9A/4Th7KIYjViIC-i1MSV_XGFh5GlRFlwxqgCLcB/s1600/3063%2BTeal%252C%2BTitchwell%252C%2B27-Jun-16%2B%2528A%2529%2B%25283%2529%2BL.JPG

This is one of the rarer cases of an intersex Mallard showing some flank barring:

http://1.bp.blogspot.com/-WK4OhW6vhsE/VKl6AlHRiSI/AAAAAAAAETM/pqAC8fR--P8/s1600/1029.jpg