Saturday 17 May 2014

Olive-backed Pipits and my Tree Pipit mis-ID on Hegura

Last week I erroneously posted that I found two Tree Pipits on Hegura. I made a snap ID before having to dash for my ferry but I've no excuse for not picking up the mistake before posting! The pipits in question are clearly Olive-backed, however they are still of interest.

For years I used to look for yunnanensis without luck around Kyoto. About 25 years ago I'd been told it was a winter visitor to the region and therefore I had assumed it would also be a relatively common migrant. Despite checking primary projections on all birds I saw well enough, this was the only feature I'd been told could be used to separate the local hodgsoni and yunnanensis, I never did find any and concluded either they don't occur as often as I'd been led to believe, or they weren't sufficiently distinctive to ID in the field or that I just wasn't looking hard enough. I'd long since given up even thinking about them by the time the Birds of East Asia (Brazil 2009) came along and confirmed the Japanese population of hodgsoni has a longer primary projection than their continental counterparts. It suddenly  struck me I'd been barking up the wrong tree all that time. When I was told about continental birds I jumped to the conclusion that the birds referred to were yunnanensis, it seems not.

The two shots of the above crisp-looking February bird has a minimal primary projection and is interesting to compare with the following 30 April individual which has an easily visible primary projection. Whether this difference is sufficient to draw any conclusions regarding Japanese or continental populations I don't know. Trying to find a difference between populations of the same subspecies might in any case be a pointless exercise. Still, it has rekindled my interest in these birds and now that I have a camera it might make judging them easier.

The two birds I misidentified on May 6th were on the 'the green' in the harbour, I walked right past them once then deciding I'd better get on the ferry turned and almost trod on them. How I'd missed them on the short grass is beyond me. They flew up onto a fence, I looked at one of them through the bins and... ahha, Tree Pipits. I rattled off a few shots and ran for the ferry. Well, that's my excuse anyway.

One of the two landed on top of the fence and I paid it more attention as the other was partly hidden. I've never seen such a worn and brown Olive-backed and it's worth stressing the shots were taken six days after the fresh bird above. I think these two Hegura birds are actually yunnanensis on the basis of the very fine Tree Pipit-like flank streaks on both, as well as the lack of pre-breeding moult on one, which might suggest they belong to a far more northerly breeding population (or just that it is delayed for some other reason), and the very plain mantle on the other. As yunnanensis is the race breeding in Hokkaido this doesn't seem such a big deal but they are the only migrants I've seen that do appear to be this subspecies. Or at least the only two that look like this. Perhaps ultimately that I haven't been trying hard enough is the reason I haven't found such birds before.

Below are shots of the two Hegura Olive-backed in question.

Superficially unlike the Olive-backed I'm used to because of overall brown colouration. Lateral crown streaks not outstandingly darker than crown streaks, supercillium relatively dull compared to wing bars, very fine sparse flank dashes and rather black wing coverts with prominent white tips creating quite bold bars.

Incredibly worn tertials and little sign of any new pre-breeding feathers anywhere.

The exceptionally worn state of the plumage led me to suspect 2CY but the uniformity of the coverts suggests otherwise.

Self-shading reveals a creamy throat and breast with sharp demarcation to the white belly.

The second pipit is in much fresher plumage. The very fine dashes on the flanks and plain upperparts look quite different to the OBPs I'm used to seeing and I guess this must be yuannensis. I'm still puzzled why I've never seen birds like these before.

Just to prove Tree Pipits do occur on Hegurajima, I found this first autumn bird one September a few years ago.

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