I was running on autopilot and vodka fumes yesterday as I was extracting Robins and Wrens during the first net round. It was a dark and gloomy morning and, in the half-light, I went to extract a "robin" from the bottom shelf of net 4 in the lighthouse garden. The bird rolled slightly as I pulled the net towards me and... holy fuck, it had orange flanks. And yes, a blue tail. I held the bird and turned to
Marcel, who was at the far end of the net. “Marcel, come here! Come here!” I shouted, with a generous sprinkling of profanity. Then I remembered what he had done with the subalpine warbler in spring, telling me to wait around the corner until the bird was extracted and I could enjoy the full impact. “No, stay there Marcel! Stay there!” I rearranged the bird in my hand so that only the tail was visible, then I lost it slightly. “It's blue! It's blue!” I shouted at Marcel. Of course he had no idea
what was blue... until he came over and saw it for himself.
Sod's law dictates that good rarity weather equals crap photography weather, and yesterday morning was no exception. The sky was grey and low, and since the bird was caught in the first net-round there was an almost entire lack of sunlight in the lighthouse garden. Not that you need much light to document the salient features of a Red-flanked Bluetail but still... IOS 800, f5.6 and a 1/15th second shutter speed don't make for award winning photographs.
The bird was straightforward to age, showing an obvious moult-limit in the greater coverts (seven unmoulted).
The bright blue lesser coverts and the blueish tinge to the moulted greater coverts should allow us to confidently sex the bird as a male.
Svensson (1992) states that inside of upper mandible in first-years "yellowish, sometimes browner at tip" (with the footnote that this is taken from skins). It's the only ageing criteria given. I know that there is at least one British record of bluetail aged, from what I've heard, using the inside of the upper mandible. I've always been suspicious and yesterday's bird didn't help to relinquish those suspicions. I wonder how many people would age this bird as an adult if inside of the upper mandible was the only characteristic they were using.
I guess I can't post a blog post about a Red-flanked Bluetail with a photo of
that tail.
Yesterday's ringing didn't stop with the bluetail. We caught nearly 500 birds, including 43 redpolls, 80 Common Chiffchaffs (mostly
abietinus, some
collybita and one good
tristis candidate) — equalling the previous chiffchaff day record — and our first big Bullfinch of the year.
As if that wasn't enough ringing for one day, Peter Olsson, Albin and I opened 162m of assorted mesh-size mist-nets north of the garden just after dusk and, by midnight, we'd managed to catch a Long-eared Owl, a Moorhen and two Water Rails.
The owl is a 3+cy female. The secondaries show five reasonably broad dark bars.
Compare that to this first-year that we caught last year:
A closer look at the secondaries of last night's bird shows what appears to be a moult suspension limit in the secondaries, with the inner three or four moulted.
The outer three also appeared to be moulted, though the difference is subtle.
Critically for ageing as a 3+cy, both the old and the new secondaries show adult pattern; i.e. it is replacing adult secondaries with adult secondaries, so it must have undergone at least one complete moult prior to this one.
The primaries, or more correctly the primary coverts, also showed what appeared to be a moult suspension limit. You can see that the outer primary coverts are browner and appear more worn, though with owl's loose and fray-edged plumages I find it hard to assess wear sometimes.
According to the literature, adult birds moult all primaries so perhaps this bird will continue moulting primaries after migration. The suspended primary moult also explains the seemingly rather limited secondary moult (though per BWP, the range for retained secondaries is 0–6; this bird shows 6, so it might not be *that* limited).
The bird can be sexed on the overall rather brown-orange ground colour of the plumage, the dark face, and the orange-buff inner webs to the secondaries. Compare with last year's bird, a male, which has a whiter ground colour to the plumage, paler face, and white inner webs to the secondaries. I don't know if the primary pattern on the underwing is a consequence of age, sex, or both.
