What do YOU think?
by Martin G.
Here’s some features. I am inclined to think this bird can be aged as ………
With very big nod of appreciation for help with this post to the Wildfowl and Wetlands Trust at Slimbridge, particularly warden James Lees (over several years!) and other staff and to Tony Disley.
Haven’t seen the bird (yet) but have followed the unfolding story of the drake Baikal Teal at Marshside, Southport. Found amoung wintering Wigeon and Teal, it fully ticks the ‘arrived wild’ boxes for me. Given the central Asian breeding range of some of the Wigeon which winter in Britain, I suspect some individuals could even alternate wintering grounds between the Eastern Atlantic seaboard and the East Asian Pacific Rim (just as Pochard have already been shown to do, alternating between Slimbridge WWT and the Sea of Japan!).
As many of the vagrant birds which reach Britain are in their first year, the aging of vagrant wildfowl is of real interest. So what age is this Baikal Teal?
I have explored this subject a lot, tearing hair out many times and have still not crystallised what features are most helpful to aging. It’s tricky, really tricky! So rather than a definite list, here’s some hypotheses of what might work but still needs more testing. See what you think. And on the Southport bird I would target field impression and photos of the flank feathers, specula (white trailing edge) and long lanceolate scapular feathers. That should sort it
(above 2) Same captive adult male Baikal Teal, Sewerby Hall, East Yorkshire, 6th December, 2013. Martin Garner. The colour, patterns and distribution of the flank feathering, together with the pattern and length of lanceolate scapulars help with aging. This one has temporarily ‘lost’ the black tear drop and it will appear as fresh feather fringes wear down.
4 Key Characters to explore
Both adult and first winter Baikal Teals moult out of a brown plumage into the resplendent male ‘breeding’ plumage. In some examples adults moult out of brown ‘eclipse plumage’ at least one month ahead of 1st winters moulting out of full brown juvenile plumage. So some adults can be in nearly full plumage by early December, some 1st winters still have a good mix of brown body feathers in January. But there is overlap. At least in studying captive birds, in early December, they can look remarkably similar. In the case of the Southport bird the amount of retained brown flank feathering can be pretty much matched by both adults and first winters, so moult timing is arguably not very helpful in aging the Southport bird.
There appear to be subtle differences in shape patterns and colouring off the brown eclipse feathers and brown juvenile feathers. Slightly richer warm chestnut in juvs with more obvious fringe and paler, sandy coloured on adults with paler internal section. Not easy to read in field as can be obscured by overlapping feathers. Also perhaps differences in the distribution of retained brown feathers on the flanks. e.g more random in adults, more of neat line on upper flanks in first winters. Just an observation on few examples. Needs more research. See photo: 1st winter on left. adult on right, 6th Dec. 2013 by James Lees, WWT
There appears to be some small but notable differences in the lanceolate scapulars. In adults the obvious long feathers are striking and contrastingly patterned with broad black centres, obviously broad/very broad on 2+ feathers and contrasting with broad creamy white or off-white inner web. In first winters the same feathers average a tad shorter, the black is on average more narrow (being broad only on the longest feather) and the inner web of the feather is muted buffy/ pale brownish, contrasting much less than in adults. I noticed differences in width of black a while back but it was Tony Disley that clocked the differences in hue of the pale inner web. Have a look at known age adults and first winters to see what we mean. Needs more testing. See photo: 1st winter on left. adult on right, 6th Dec. 2013 by James Lees, WWT
Looks pretty good feature, just needs really good photos to capture the details in the field. On juvenile secondary feathers, the white is essentially present at the tip, only on the outer web. On adults the white extends right around, fully covering the tip and onto the inner web. The shape of the secondary tip is also different, with, in simple terms more of ‘hook’ shape on the juvenile feather. See photo: 1st winter on bottom adult on top, 6th Dec. 2013 by James Lees, WWT
There’s a bunch of minor features which may have merit but much harder to work with on a bird in the field and need more testing. 1) There’s a subtle difference in pattern of back and rump feathering – would need really good photos to capture it well. 2)Tail feather shape of juveniles should be useful but they either have moulted or doesn’t work. 2) Juvenile primaries are a little slimmer, more tapered at tip and little more worn (same with primary coverts. Small wing coverts also have very faint pale fringe on juvs. 3) Tertials are tad shorter and narrower in first winter but same pattern as adults. 4) Undertail coverts can have same pattern or some, late moulting first winters have lot less black. 6) Specula very similar. On adult green and black reaches penultimate outer feather whereas on first winter 2 outer feather slack green and black- subtle! 5) White line over eye may have some merit see here. 7) Some 1st winters retain scapular feathers are which are broad and more rounded versus normally mostly pointed in adults.
The Southport Bird