Breydon Water

9th April 2009

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An early morning trip to Breydon was almost scuppered before it started when I got to the station without my wallet. Fortunately I got hold of Cathy, who got there and lent me some money for the train! When I arrived there were only three birdwatchers there, the birds finder (Peter someone), Ben Lewis (looking for Bitterns if anyone from the RSPB reads this) and another helpful local birder. We watched the plover from around the corner adjacent to the railway line for an hour or so, gaining flight views when a couple of walkers flushed it. By this time another 10-15 birders had arrived. Views were split between Pacific, not sure and impossible to id, interestingly I didn't hear anyone put forward a good case for it being American, other than initial impression.

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Being too tight to pay to access the ID paper from British Birds 2004 (and not hardcore enough to have had it in the first place!), my ideas are mostly based on the ID criteria from the Byrkjedal & Thompson book "Tundra Plovers" summarised below.

There are 10 field markings/criteria put forward that vary between juvenile or non-breeding American & Pacific Golden Plovers. As no-one has heard the bird call, that one is useless. Two refer to primary length (past tail and vs tertials), but as the bird appeared to me and several other birders to be in a state of partial moult, probably non-breeding to breeding, these are unsafe too.

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This leaves:

1) Structure: PGP has a plump body and slender neck, AGP uniformly slender. From my observations when the bird stood to attention, I would say Pacific for structure.

2) Bill length: PGP has a bill backward projection past the eye, AGP to the eye. Ben's pictures prove the projection goes past the eye, so Pacific.

3) Tibia length: PGP has longer tibia, around the length of the bill or more, AGP has a tibia of half its bill length. From observation I think the tibia were definitely longer than half bill length, so Pacific.

4) Toe Projection: On AGP the toes either don't project or only do so fractionally, whilst on PGP most of the toes are visible. I couldnt see either way in flight, it was too quick, but again Ben's photos suggest toe projection, so with less certainty than the first 3, it suggests Pacific.

5) Back Colouration: PGP is yellow, AGP is pale yellow. Although the lighting plays a part here, the back definitely appeared golden to me. The book doesn't mention colour of the chest, which I have heard is suggestive of American on this bird because of the grey, but sticking to back, its another Pacific character.

6) Supercilium: AGP is broad and white, PGP less broad and yellowish. Whilst the supercilium did look off-white to me, it was very clear, so I don't think it convinces me either way. Tie.

7) Crown contrast with nape and face: PGP moderate, AGP very much. This is the only feature I think is in favour of American, because like the supercilium, I noticed a strong"capped" appearance. American.

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So there we go. It should be noted I have no field experience of either species prior to this bird, and I am aware that they can be so similar that it is impossible to separate them, but I think there is a good case for it being a Pacific Golden Plover with a well-marked face! As the bill has been shown to be a good PGP feature, it would be interesting to see if any research papers can give a table of variation, i.e. is bill size reliable enough to clinch ID regardless?

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I'm getting a bit bored of editing this post, so this is my final word! When I was there, I was reasonably happy it was Pacific, based partly on the fact that the short tertials could be related to moult, which was the right time period. More observers then concluded the bird wasn't in moult, and was a fairly straight-forward American. Since then, the bird has called and this seems to suggest/clinch Pacific, and notably repeat observers seem to favour Pacific still. I'm coming round to the idea that I'll find out the final ID decision in 2009s Bird & Mammal Report!

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Read what people who have actually seen Lesser Golden Plovers before have to say here:

http://www.birdforum.net/showthread.php?p=1451798

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Also at Breydon was a Black Redstart, my second of the year, and I also saw a Yellow Wagtail from the train somewhere before Acle.

[Edit] Despite the characters mentioned here, it was evenutally decided that this bird was an American Golden Plover, and was accepted as such by the Norfolk Rarities Committee.