ML131957981
Green-winged Teal (Eurasian x American) Anas crecca crecca x carolinensis
Contributor
Date
Location
- Age
- Not specified
- Sex
- Not specified
Observation details
A Common Teal was reported at this location the evening before by Dean Ware on ONTBIRDS (http://ontbirds.ca/pipermail/birdalert_ontbirds.ca/Week-of-Mon-20150316/077017.html) Upon arriving at the location, we quickly focused on a bird showing a little bit of white feathering at the top of where the vertical spur would normally appear on American Green-winged Teal. In one of the photos it appears there may be somewhat brighter white markings below the eye separating the green and red feathers on the face of this bird. In other respects, the bird was not much different from nearby American Green-winged Teal (AGWT). Further research shows that neither crecca nor nimia ever show white feathering in the area where the vertical spur appears on AGWT. David Sibley discusses intergrades on his blog and raises some helpful points (http://www.sibleyguides.com/2011/03/distinguishing-green-winged-and-common-teal/): "Intergrades can show various combinations of features. Many look intermediate in both of the parental white stripes as shown above, but others can express one white stripe fully while showing only a hint of the other. I have seen a few individual teal showing neither of the white stripes and these might be intergrades as well." "A small but significant percentage of Green-winged Teal show a reduced white vertical bar on the breast-sides (shown below, perhaps 10%, depending on how “reduced” is defined). This is probably too frequent to be attributed to intergradation, but an individual that also shows slightly increased white on the scapulars, or another feature tending towards Common Teal, might be suspect." While Sibley is cautionary regarding the identification of birds with "reduced" vertical bars as intergrades, his illustrations are also helpful in separating "reduced" from almost absent. The third painting under intergrade birds shows "another frequent intergrade variant, this one showing the white scapular stripe of Common with just a trace of the white breast-side bar of Green-winged. Only a few whitish feathers separate this bird from a "pure" Common Teal." This illustration comes closest to matching the vertical spur on the bird we observed. The following illustration shows a "Green-winged Teal with limited white on breast-sides. Birds like this might be intergrades, but occur with relatively high frequency so are presumably within the normal range of variation of Green-winged." This painting shows a bird with a full but thin white spur. Considering that the vertical white spur on the bird in question is limited to a few feathers at the top of where it would normally occur on AGWT, I believe this is beyond the extreme of an AGWT with a "reduced vertical bar, and believe it is a probable intergrade. The second bird shows a horizontal white stripe in addition to a vertical white spur along with more pronounced whitish marks on the face, a much more classic combination of field marks for an intergrade Green-winged Teal. Link to short video of the birds: https://flic.kr/p/qMXMzZ
Technical information
- Model
- iPhone 4
- Lens
- iPhone 4 back camera 3.85mm f/2.8
- ISO
- 125
- Focal length
- 3.9 mm
- Flash
- Flash did not fire, auto
- f-stop
- f/2.8
- Shutter speed
- 1/120 sec
- Dimensions
- 1515 pixels x 1082 pixels
- Original file size
- 457.85 KB