thoughts on yesterday's (9/21) duck from Oso Flaco


Kevin Zimmer
 

Jim Royer asked if I would post my analysis of yesterday's duck, studied by at least 4 observers (I should stress that I was not among those who saw the bird in life), and initially thought to be a possible Garganey, from Oso Flaco Lake. So, here goes.

When first sent 2 screen-grabs from the back of the camera and asked my thoughts, I ventured that the facial pattern was suggestive of a female Garganey, as was the size of the bill, which looked proportionately large in one of the 2 photos. But, in those tiny photos (as viewed on my phone), I could see no detail on the folded wing, and there appeared to be some orange color along the juncture of the bill, which I knew was problematic if not an artifact of ambient light or camera exposure.

A short time later, Jim emailed me a whole series of photos, which I was able to examine in greater detail on my computer screen. With more material to work from, I concluded that the bird had to be a female Green-winged Teal for the following reasons (as originally iterated to Jim last night):

After looking at all of the photos, I am thinking this bird has to be a female Green-winged Teal. It looks a bit paler overall than usual, but it also looks as if these photos may be a bit overexposed, and that could account for the pallid look. It has a bit stronger facial pattern than most female GWTE, but not outside the range of variation. When I looked at the first 2 photos on my phone, the bill appeared proportionately large, but when viewed on my laptop, the bill looks consistently small, which is better for GWTE and wrong for Garganey.

Most importantly, in several of these photos, you can see a sliver of the wing speculum, and it is clearly shining green. The speculum in Garganey is fairly colorless — sort of a slate-gray, prominently framed by white. It also appears as if the under tail-coverts and part of the crissum/vent are white, and that is also wrong for Garganey, which has those areas heavily mottled and streaked with brown. I checked that against my photos of the Waller Park bird from 2017.

It’s hard to be 100% definitive, because the photos seem to have been taken at a fair distance, but I’d say the bill size, white vent and (especially) what appears to be a shiny green speculum in the wing rules out Garganey. Also, although it may be just a matter of perspective, in one photo, the bird appears distinctly smaller than a nearby American Coot, which also suggests GWTE rather than Garganey.


Kevin Zimmer
Atascadero

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