How can I tell the difference between Eurasian teal female and American Teal female ? (2 Viewers)

[Xelioszzapporro!!]

The males look identical at first glance. But u can easily distinct them from one another by the white lines on their bodies.

But I really have a hard time telling the difference between an American Teal (Anas Carolinensis)female and an Eurasian Teal (Anas Crecca) female....if somebody knows please let me know fellas....

 

[nartreb]

Good luck! First I'll note that the American Orn. Union is a holdout and considers these as two subspecies of "Green-winged teal", contra everybody else.

Audubon.org says "female not safely identified" as to American vs Eurasian. If you check the more reputable websites (Audubon, Cornell, etc) you'll find that photos of males are consistently labelled "American" or "Eurasian" but photos of females are only labeled when they're accompanied by a male. They don't even distinguish between "female or immature."

 

[jurek]

Every source I know of says it is not possible in the field. There are some indications but large overlap.

 

[Joern Lehmhus]

So lumping the two seems the logical consequence. However, as far as I remember the problem with lumping the two might mean you would have to lump them also with Anas flavirostris in classical views:
Johnson & Sorenson (1999) found a deep mitochondrial DNA divergence between Anas crecca and carolinensis,
and the latter was sister not to Anas crecca but to Anas flavirostris from South America, which is quite different from phenotype and behaviour.

Maybe this information is by now outdated though...

 

[smiths]

There is a useful difference in the pattern of the tertials according to the recent (and excellent) Identification Guide to the Ducks of Japan, although I have not checked this against an extensive series of photographs yet myself.
There are also subtle differences in overall colour, head pattern and colour of the wingbar in front of the speculum.

 

[Joern Lehmhus]

There is a useful difference in the pattern of the tertials according to the recent (and excellent) Identification Guide to the Ducks of Japan, although I have not checked this against an extensive series of photographs yet myself.
There are also subtle differences in overall colour, head pattern and colour of the wingbar in front of the speculum.

what kind of difference is that?

 

[jurek]

So lumping the two seems the logical consequence. However, as far as I remember the problem with lumping the two might mean you would have to lump them also with Anas flavirostris in classical views:
Johnson & Sorenson (1999) found a deep mitochondrial DNA divergence between Anas crecca and carolinensis,
and the latter was sister not to Anas crecca but to Anas flavirostris from South America, which is quite different from phenotype and behaviour.

A later publication (mentioned here at BF) found that this is an artifact, and Eurasian and Green-winged Teals are sibling species, as might be expected. However this was ignored, as virtually any evidence of lumping any species together.

 

[Southern Viking]

what kind of difference is that?

Pretty sure there was an article in Birding World some years ago that discussed the differences Smiths mentioned, including tertials and wingbar, as to the details - I can't remember! Something to do with distribution of white and orange in the greater covert bar? I must have the BW article somewhere but it'd take ages to dig out

 

[Stephen Dunstan]

https://britishbirds.co.uk/sites/default/files/2019_V112_N01_35-43_femGWTeal.pdf

includes the relevant illustrations from the Japanese guide

 

[Joern Lehmhus]

Thank you very much, Stephen!

 

[Xelioszzapporro!!]

https://britishbirds.co.uk/sites/default/files/2019_V112_N01_35-43_femGWTeal.pdf

includes the relevant illustrations from the Japanese guide

Stephen thank you a lot for this...I almost thought there was no way to differentiate them but at long last thanks to you I see light in the end of the tunnel
Very informative and rare identification link sir!