WHITESTRIPES

A GUIDE TO GREEN-WINGED TEAL

by Ian McKerchar

Drake Green-winged Teal at Marshside, Merseyside by Adrian Dancy

Green-winged Teal (Anas carolinensis) is the American counterparts of our own Eurasian Teal (Anas crecca) and was formerly considered to be merely a race of the latter but in December 2000 it was given full specific status by the British Ornithologists' Union's Records Committee, with the American Ornithologists Union adopting the same split in 2002.

Eurasian Teal is fairly common in it's current county status with an often large wintering but now all too rare breeding population and can invariably be found in our county throughout the year. Green-winged Teal however, is a very rare vagrant to Greater Manchester with currently only five records and despite it's national status clinging on as an 'unofficial' rarity it was dropped from the list of species considered by the British Birds Rarities Committee in 1990 with just over 440 records having been accepted!

So, identification then...

The identification of drakes seems pretty straight forward on the face of it really, what with drake Green-winged Teal having an obvious vertical white stripe at the front of the flanks and Eurasian Teal not, but things aren't always all that straight cut. Sure, any drake with said vertical white stripe at the front of the flanks is going to scream Green-winged at you but they have a few more, often quite subtle features that differentiate them from Eurasian Teal and with drake Green-winged Teals often long-staying on this side of the Atlantic the inevitable interbreeding with our Eurasian Teals occurs and hybrids are born. Atleast we get our own back on the 'Yanks' with our Teals (and also the Asian race of Common Teal, Anas crecca nimia) getting across to the USA and giving them 'hybrid trouble' too!

Separating Drakes

Whitestripes

Green-winged Teal of course carries an obvious vertical white stripe at the front of the flanks which Eurasian Teal does not and this remains the single most striking feature to look out for when scanning through a flock of Eurasian Teal in the hope of something 'better'! Green-winged Teal also lacks the horizontal white stripe above the flanks (as seen on a resting or swimming bird) which is normally very conspicuous on Eurasian Teal and clearly broader than the black stripe immediately below it, although it should be borne in mind that at times part or infact all of the horizontal white stripe on Eurasian Teal may be concealed by feathers.

Above: Eurasian (left) and Green-winged Teals at Fernhill Wetlands, Forest Grove, Oregon, USA by Greg Gillson (www.thebirdguide.com).

On the above photograph the various 'whitestripes' are easy to see, with the Eurasian Teal's conspicuous broad horizontal white stripe above the flanks and the Green-winged Teal's equally conspicuous vertical white stripe at the front of the flanks but note that the latter has a inconspicuous buffish/grey horizontal white stripe above the flanks where the Eurasian's is white.

'Headlines'

Both species have reddish heads and a green patch on the side of the head although the reddish colour on Green-winged Teal tends to be darker chestnut with perhaps an often darker (almost blackish) forehead and chin.

The creamy lines around the green face patches on Eurasian Teal are usually evenly conspicuous and broad whereas those on Green-winged are very poorly marked and faint with usually only a creamy line under the eye and cresent in front of the bill.

Above: Green-winged Teal (left) at Marshside, Merseyside by Sean Gray (www.grayimages.co.uk) and Eurasian Teal (right) at Pennington Flash, Greater Manchester by John Tymon.

Note the creamy facial markings on these two individuals above, their distribution and strength. Note also that the Eurasian Teal, taken in October, still has remnants of eclipse plumage and that it's breast has an apparently slightly pinkish hue normally a feature of Green-winged (which see below for discussion).

Lines, lines and more lines

The flanks of Green-winged Teal often appear a smoother, slightly darker grey due to finer, more dense vermiculations (black and white lines), where the flanks on Eurasian Teal can appear paler due to the coarser vermiculations on the feathers where the white is more conspicuous and broad.

On Eurasian Teal there is usually a rather obvious pale line in front of the black 'bar' on the undertail coverts which is much reduced or indeed lacking on Green-winged and although there appears to be a fair amount of variation within this feature, it is useful as a supplementary character atleast.

Above: Green-winged Teal (left) at Marshside, Merseyside by Adrian Dancy and Eurasian Teal at Pennington Flash, Greater Manchester by John Tymon.

Note the relative strengths of flank barring between the two species in the images above and the virtual absence of a pale line infront of the black bar on the undertail coverts of the Green-winged compared to the obvious one on the Eurasian Teal.

And now for some colour...

In Green-winged Teal the breast colour is often brighter, more pinkish with heavier markings, especially compared to the paler, more sparsely marked breast of Eurasian Teal but again this feature should be used in conjunction with other features as the breast of Eurasian Teal can occasionally appear warmer in tone and more similar to that expected of Green-winged.

Above: Green-winged Teal (left), Marshside, Merseyside by Sean Gray (www.grayimages.co.uk) and Eurasian Teals at Pennington Flash, Greater Manchester by John Tymon.

The breast colouration of the Green-winged Teal in the above image is clearly a bright and quite uniform pinkish but the two Eurasian Teals on the image to it's right display the variability possible, with the left hand bird showing a slight pinkish hue and the right hand bird the more usual paler colouration. Note and compare the strength of breast markings on all the birds.

Speculum borders

In both male and female Green-winged Teal the leading edge of the speculum on the upper wing seen in flight is more often cinnamon/buff, whereas in Eurasian Teal the same border is usually whitish but there can be sufficient overlap in this feature between the two species to render it's use as cautious and supplementary at best.

Separating females and immatures:

There has been a certain amount of discussion on the possible separation features of females (and immature) Green-winged and Eurasian Teals in birding literature over the past few years, when up until that point it had been taken for granted that their separation was impossible. These features have laregly involved the facial pattern which has been alleged to be more pronounced and contrasting in Green-winged Teal with a dark horizontal line through the eye and similarly through he cheek with a pale cresent or spot at the base of the bill. There have also been other features 'touted' but for my personal experience, which involves basically ignoring many hundred female Green-winged Teals in America but carefully studying many more Eurasians in the UK, the variability within the facial patterns of Eurasian Teal makes the confident identification of female Green-winged Teal very difficult to say the least!

Above: (Left image) Drake Eurasian Teal with female Green-winged Teal at Fernhill Wetlands, Forest Grove, Oregon, USA by Greg Gillson (www.thebirdguide.com) and (right image) male and female Eurasian Teals at Pennington Flash, Greater Manchester by John Tymon.

Is there enough to confidently separate the above two female 'teals' from their facial patterns in these images, let alone convince a rarity committee? It shall be a brave birder who claims the first, on Greater Manchester's soil anyway! Note here, the horizontal white stripe above the flanks on the drake Eurasian Teal on the right image is indeed being concealed by feathering apart from a very inconspicuous 'sliver' towards the rear.

The hybrid problem

Above: The Happy Couple! Drake Green-winged Teal and female Eurasian Teal at Marshside, Merseyside by Adrian Dancy.

Stuck on the wrong side of the Atlantic, single, bored and lonely- well you would wouldn't you? And they do!

Hybrid Green-winged x Eurasian Teals have been recorded in the UK on more than a couple of occasions and the same is true in America when our randy little blighters get across there, so just how do we identify a hybrid drake Green-winged x Eurasian Teal (forget females all together!)?

It's not necessarily all that difficult as it appears that atleast most display some characteristics of both species, although as the hybrids back-cross and their 'best of both world' characteristics become watered down things may yet become more complicated. Careful study is therefore necessary of any Green-winged Teal that appears to show odd features.

Anyway, the images below, all courtesy of Greg Gillson (www.thebirdguide.com) were taken at Fernhill Wetlands, Forest Grove, Oregon, USA.

Above: This drake (foreground with a drake Green-winged Teal in the background) above shows the typical mixed characteristics of a hybrid with the bold horizontal white stripe of an Eurasian Teal and the equally bold vertical white stripe of a Green-winged Teal. The creamy face lines are too strong than expected for Green-winged Teal, while there is little pale rear flank line and the flank and breast patternation/colouration all lean towards Green-winged.

Above: This hybrid (left, with a Green-winged Teal on the right) has only the very faint vestiges of a vertical white stripe in front of the flanks but a strong horizontal white stripe above the flanks and whilst not as clear cut as the hybrid in the image above, it clearly displays characteristics of hybridization.

Acknowledgements

My sincere thanks are due to the photographers whose superb images have once again enlivened another boring slab of words and whose generosity knows no bounds, they are: Adrian Dancy, Greg Gillson (www.thebirdguide.com), Sean Gray (www.grayimages.com) and John Tymon.

References

Vinicombe. K. E. (1994), British Birds, Vol. 87, No. 2. Common Teals showing mixed characters of Eurasian and North
American races

http://thebirdguide.com/identification/Eurasian_Teal/teal_hybrid.htm

 

Ian McKerchar, January 2008

Bottoms up! Green-winged Teal at Marshside, Merseyside by Adrian Dancy.

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