Aging and gaps in the wing
by Martin G.
It stayed for one day only and left with the same 2 female Eurasian Wigeon that it arrived with. By way of follow-up here are some comments on:
- why it’s most likely a 2nd calendar year (1st winter/summer) male
- timing of the species migration
- why those apparent gaps in the right wing
Some folk wrote in, others help with photos. THANK YOU for help with this post to Brett Richards for a most gripping find and much lively discussion as well as Nial Moores, Anthony McGeehan, Richard Millington, Adrian Kettle, Steve Race, Dave Mansell and Graham Catley.
On Migration and Aging
Nial Moores (Birds Korea):
Martin, as you know most of the world’s Baikal Teal winter in the ROK (Republic of Korea), with earliest returning birds arriving in September. Numbers increase rapidly through October into November; and the peak is probably reached in January. During northward migration the main northward movement through ROK (34D-38DN) is in early March. Most have exited the country by mid-March, with lingerers into early April (and a very few oversummering most years).
Migration phenology is perhaps less well-known for areas further north,
but believed to arrive on breeding grounds first from late April, with
egg-laying from end of May south of Arctic circle, later northward (latter
part from Baikal Teal account in series Bird Families of the World
published by OUP). Timing of Flamboro’ bird therefore seems consistent
enough with timing of northward movement towards breeding areas, where-ever the bird spent the winter.
Have had multiple discussions in the past about ageing. As caveat, believe
that people with access to and understanding of captive birds of known age
can develop and start to test criteria with much greater confidence than we
can here. Usual encounters here with Baikals are of flocks – which are
often quite mobile (birds peeling off the edge to get closer to the centre
again, as well as between sites) and these flocks can be huge (the largest
single flock I counted contained an estimated 671,000 birds!).
Drake Baikal Teal (probably 2cy), Flamborough, 15th April 2013. Graham Catley.
The few criteria that I use to (tentatively) age birds were therefore
developed through comparing birds in flocks. In Sep. most Baikal males are
very dull. In many, however, the head pattern and breeding plumage body
strengthens through October, and by early November many males are back in
br-type plumage and then start to display and pair up. Some males, however,
do not develop full br-plum until much later in the winter (January or
February). Based on this timing (and behaviour), I assume that adults tend
to develop full breeding plumage 2-3 months earlier than First-winters. In
direct comparison, these presumed adults tend to have darker bills and the
typical male BT head shape; longer, cleaner-patterned lanceolate
“super-scaps; cleaner head-markings (with cleaner iridescence on the head,
and cleaner white markings); and more extensive (broader, longer) white
breast stripe on the fore-flank. In direct comparison, birds presumed to be
First-winters often seem to show some paler grey tones in the bill towards
the base; a less full-looking nape and crown (i.e. a head shape not so
dissimilar to females); less well-developed and less distinctly-patterned
super-scaps; dirtier looking white areas and less clean iridescence on the
head; and a less obvious white breast stripe. Some of these differences can
be apparent as late as March (and presumably into April – when most have
already departed from the ROK). I was not aware of/have not been looking
at the iridescence of the speculum – but have wondered a little about the
colouring of the tips to the greater coverts.
Drake Baikal Teal (probably 2cy), Flamborough, 15th April 2013. Steve Race. All 10 secondaries are present on the right wing with one feather being displaced
Drake Baikal Teal (probably 2cy), Flamborough, 15th April 2013. Dave Mansell (East Ayton Birding). In all 3 photos above the pattern of green on the specula is restricted to the inner secondaries.
Wing of Adult male Baikal Teal (in captivity, Feb. 2010) Slimbridge WWT, Martin Garner, (thanks to James Lees) showing green extending of green on the specula is greatest in adult males and reduced in young males.
Juvenile male Baikal Teal, Chigborough Lakes, Essex, 2nd October 2010. Adrian Kettle. This bird also a one day stayer, also arrived with as small flock of Wigeon, also looks like the green in the speculum is restricted to the inner part (c outer 4 secondaries not visible), also had some pale grey at the bill base (present but little less obvious on Flamborough bird) and as the Flamborough bird seems to be, is also a young male. Indeed of the 4 previous accepted British records, all have been 1st winter males and all apart from the Oxford bird (which was unaged).
If these criteria are correct then based on the images on Surfbirds I
would age the Flamboro’ bird as a 2cy. There seems to be nothing odd about
the structure or the plumage of the Flamboro’ bird either (apart from it
looking a tad on the large size, and the shortness or absence of one of
those super-scaps on at least one side of the bird). The feel of this bird
is therefore to me, spot-on for a pure Baikal (unlike, I regret to say, the
super-chunky-looking Minsmere bird a few years ago – again, though, this
impression based only on images posted on Surfbirds).
Finally, FYI, the massive increase in this species appeared to peak in
winter of 2008/2009 (when >1 million counted in the ROK); since that time
there seems to have been another very rapid decline, at least in the ROK
(down to probably only c. 300,000 or so this past winter).
We don’t have so many easy-access images of Baikal Teal; a few images are
in our gallery (here) and others can be found through our websites’ search function.
Hope this is useful in some way,
Best wishes and birding,
Gaps in the Wing
Lots of birds get gaps/damage in their wings. Lots. Deciding if these are the product of something caused by humans or a phenomenon of the bird’s activity is a curious art! Some further thoughts:
Drake Baikal Teal (probably 2cy), Flamborough, 15th April 2013. Martin Garner. Gaps in the wing. Some apparent damage? All 10 secondaries are present (see above) and 9 of the 10 primaries are visible here. That makes potentially a single missing feather. So what does that mean?
First winter Pink-footed Goose, Inishbofin, november 2012, Anthony McGeehan.
Adult male Baikal Teal (in captivity, Feb. 2010) Slimbridge WWT, Martin Garner, (thanks to James Lees)
Drake Baikal Teal (probably 2cy), Flamborough, 15th April 2013. Brett Richards. Compare Flamborough bird with captive adult male above. The central long ‘super’ scapular has narrrow black strip- apparently normally much broader in adult birds. Several captive 1st winter drake Baikal Teal had a similarly narrower black stripe on the same feather (original obs MG 2006). Furthermore notes on museum specimens indicate that in adult males the long thin white stripe above the eye, runs right into the bill base whereas on 1st winter males the white long can ‘break down’ above the eye. On the Flamborough bird the white stops juts above the eye and the area is yellow as it runs towards the bill base. A photo of the first British record taken in Essex in January 1906 (British Birds Vol 102 page 693) appears to show the same speculum pattern and the same head pattern as the Flamborough bird.
Drake Baikal Teal (probably 2cy), Flamborough, 15th April 2013. Brett Richards.
and then it flew off…