Bird counts are fun

It's Thursday. Time to count some Wigeon and some Mute Swans. Weekly bird counts...

Sometimes, though, they come up trumps. The past two bird counts have given us Gyr Falcon, Red-breasted Goose, White-tailed Eagles, Bewick's Swans, Rough-legged Buzzard, Great Grey Shrike, a flock of Scaup, a Black Redstart, and some Mute Swans and Wigeon.

Most exciting find, from our point of view at least, was when we stopped the car at a random field to [half] jokingly “find a Daurian Jackdaw”. We didn't, but we did find this striking soemmerringii-type Jackdaw. I haven't got much more to say about that bird that Marcel hasn't already said over on his blog.

It's been windy for the last two days, so no ringing; and it looks like it will rain tomorrow. However, ringing at the lighthouse garden has been varied and productive over the past week or two. We've only ringed one Great Grey Shrike so far this year, a first-winter bird.

As the footnote in Svensson's Identification Guide to European Passerines points out, “it is tempting to believe that those birds of ssp. excubitor, homeyeri and others, with completely unbarred pale grey-white underparts and with jet-black lores and WF are ad. males...” Indeed, this bird, being a first-winter but still having jet-black lores, clean white underparts, and an extensively black bill, gives the impression of being what we might consider a male; but as the footnote in Svensson goes on to say, “...if we assume that males have on average longer wings than females, and if the sexing by taxidermists of skinned birds in collections of this species is not erroneous at an exceptionally high level, then barred or unbarred underparts, black or grey lores, etc. vary individually (or to extent by age?), not according to sex.” The same footnotes also points to a reference, Dohmann (1980), which found that males on average have slightly more white in the tail than females but the difference is very slight with extensive overlap. As it happened, this bird had rather limited white in the tail (and in the secondaries). It was, in the end, left unsexed.

The bird had moulted one greater covert, GC9, but on the right wing had also lost and regrown GC4 & 5. They're glossier black than the retained juvenile greater coverts, which are browner with a pale fringe at the tip. The moulted median coverts (all of them) are the same glossy black colour as the moult GCs.

While we're vaguely on the subject of variation in Great Grey Shrike, it's worth pointing out this paper. It's a shame it smells like complete bull, because I quite like the idea of them all just being colour variants. It would make like a whole lot easier. Or a lot more boring.

A Whitethroat on 31st October is always worth taking a close look at... though this one seemed to be disappointingly communis-like.

We've caught a few Redwings. Nice to take a look at variation in wing length and plumage of what are, presumably, all nominate birds.

Finally, as much for aesthetics as for education, the primary coverts of a first-year Jay. It's the only Jay I've handled this year but it didn't hesitate in adding its calling mark to my hand, along with various scabs and wounds from a Magpie, the shrike, a Great Spotted Woodpecker, and a particularly nasty Flommen reed stem.

The dark bars in the feathers develop much as growth bars do. I don't actually know what that means, I'm just repeating what I've read; although I presume the melanin deposits are turned "on" and "off" as the feather grows. So, when a set of feathers are grown at the same time – as they are in the juvenile bird in the nest – the on/off results in the same pattern forming at the same point along the feathers. I've heard this misquoted numerous times as “the bars line up across the closed wing”. They don't; but you can trace the same pattern up the length of each feather. In this case, starting at the tip, there's a medium black bar, a narrow black bar, a (very) thick one, thin, medium-thick, medium thick, etc, hideously demonstrated using coloured arrows below. The same pattern occurs on all the feathers. In adults, at least some of the PCs generally show irregularities in the barring not shown in the other feathers.