Thursday, March 26, 2009

Wagtail id

Two of these birds were amongst 50+ very obvious pied wagtails at Callis Bridge sewage works today.
White wagtail, or pied wagtail. Discuss:
(apologies for the photos by the way! Click on each one for a larger image)














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6 comments:

Nick Carter said...

White

8:26 pm
Nick Carter said...

Sorry not much discussion there!

I favour White on the following features, very pale back, the black from the nape and bib don't appear to meet and there is a contrast between the wings and the back. If I remember correctly a white should have white flanks whereas a pied can show darker flanks, can't really make my mind up on this feature in your photos, the flanks do look a bit sooty but on balance I still favour white.
I believe the real clincher is the rump? dark in Pied but pale in White, did you get to see the rump in flight?

8:59 pm
Matt Bell said...

Didn't get a good view of the rump, and just to confuse matters more, these photos are likely to be of more than one of the birds, as they were very mobile, and a were put up en masse more than once.

9:04 pm
Nick Carter said...

Darrel Prest has commented that the photos suggest a female pied as the rump looks "pretty dark" in #1,also very grey flanks and smudging on the mantle/wings. His e mail goes on to suggest the
contrast between nape and mantle is due to the light, also that there is diffusion between the wings/mantle and the nape/mantle and that the mantle colour is too dark even though it is contrasting due to the light.

Any one else got any views?

7:54 pm
AndyC said...

I have to agree with Darrel

3:28 pm
Nick Carter said...

Further discussion from Martyn

Going on what I can see from the photo's this bird is actually a female (or more probably a first-summer male) White Wagtail M.a.alba, the flanks are very clean, both sexes of yarrelli (Pied) would show a darkish grey smudge, (White's is pale grey and nearly impossible to see and often looks like a shadow when you can make it out, hence most people say there is no smudge).

I've often had this conversation with people about dullish White Wagtails, they are not always as bright as books suggest and most of us see them in bright sunlight in places like Spain etc which makes the mantle look even paler. I also suspect in all the exitment of birding overseas that they get very little attention at all! Indeed from Greece eastwards they are actually paler anyway.

This bird looks typical of what I think of as a female White of the western races, which we would get here as they travel to Iceland, it does look a little darker on pic 224 but the contrast between the nape and mantle is still clear and the flanks still look clean. It looks to have a little smudging on the face on pic 213, this is what makes me think it may be first summer male. In summary it looks typical of the female/1st summers I remember from Iceland a few years ago, (I did make a point of having a really good look)

10:05 pm

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