Mystery Bird Quiz #1 - The Answer

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sav
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Mystery Bird Quiz #1 - The Answer

Postby sav » Mon Aug 17, 2009 9:41 pm

Mystery Bird Quiz #1

This photograph of a relatively plainly marked wader was taken by Neil Fitzgerald at Miranda on 5 January 2007. The majority of respondents (25 out of 30) correctly identified it as a Tattler sp (either Grey-tailed – GTT, or Wandering - WT); based on the plain grey colouration, yellow legs and straight robust bill. A few other choices were for Red (Lesser) Knot, and that makes a certain amount of sense, but Red Knot doesn’t have such a strongly marked face, nor any colour in the bill. The yellow legs are also too yellow for Red Knot which has, at best, straw-coloured legs. In defence of those that chose Red Knot I must say that I saw a very well-known NZ birder make just that mistake in the field a few years ago!
The two Tattlers are regarded as quite difficult to separate, and this photo lends weight to that fact, since 14 out of 25 Tattler guesses were wrong. So what are the most useful discriminating features?
To my mind, the best and easiest way to tell the two apart is the tone of grey of the upperparts. Unfortunately this requires one to have comparative experience of both species, but it is true to say that WT is darker, more slaty-grey, and GTT is a shade or two lighter and often shows a brown tinge.
The length and strength of the supercillium is also important, but this individual has a rather ambiguous eye-stripe. It looks to be rather thick at the base of the bill and may meet over it. It almost stops at the eye, but has a trace of white behind the eye. Compared to GTT, WT has a more restricted supercillium which tends to be pinched in just before the eye, and does not extend past it. Allied to the strength of the supercillium is the size and shape of the dark loral stripe – thicker and better defined in GTT. Also WT has a better defined white eye ring.
The length of the nasal groove is often quoted as definitive – but it is hard to measure. In GTT it is supposed to be just over half, and in WT almost three-quarters, of the bill length. GTT tends to show more yellowish tinges at the base of the bill, with this being very restricted or absent in WT. The pattern of scales on the legs is a useless field character, and I cant make it out even on this photo – so will ignore it!
How about general size and structure? It is difficult to be hard and fast about it, but GTT is slimmer, less bulky and has thinner legs than WT. WT has longer wings, extending well past the tail.

So we should be getting close to a solution……….Our bird is fairly slim, pale rather than slaty, and has a brownish cast to the upperparts. The nasal groove is about 50% of the bill length. There is a distinct yellow tone to the basal third of the bill. The supercillium is strong, quite thick, and traces of it extend past the eye. There is no strong white eye-ring. The wings extend to about the end of the tail.
It is a Grey-tailed Tattler (Tringa brevipes), but it would be nice to have one more clinching feature – which does in fact exist. Look closely at the primaries in the photo crop below – a WT will show 4 clearly visible, with the 5th just showing, beyond the tertials. A GTT will have 3 clearly visible with the 4th just showing - as does our bird. If only we could hear it call it would be oh so easy!!

NBF_Tringa-brevipes_6351.jpg
NBF_Tringa-brevipes_6351.jpg (88.6 KiB) Viewed 8948 times


Thanks to all those who participated in the quiz. The 11 that got it right are ahead in the stakes to win our fabulous prize, but there is a long way to go yet and some of the photos may be harder than this one.

Cheers
Sav Saville
Wrybill Birding Tours, NZ
Great Birds, Real Birders
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philbattley
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Re: Mystery Bird Quiz #1 - The Answer

Postby philbattley » Mon Aug 17, 2009 11:17 pm

Sav if that nasal groove is 50% of the bill length then I need to get my eyes checked! I'd like to see some alternative shots of that bird (or the crop you mention should be below) before I concede defeat (though I conceded at the outset that my identification was as likely to be wrong as right...).

Is the judge's word final on these matters...?

Cheers, Phil
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Neil Fitzgerald
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Re: Mystery Bird Quiz #1 - The Answer

Postby Neil Fitzgerald » Tue Aug 18, 2009 9:43 am

philbattley wrote:Is the judge's word final on these matters...?


Yes. It's even in the rules :twisted:

It's not easy to tell from the small pic, but a close inspection of the nasal groove shows it to be around 50%.

NBF_Tringa-brevipes_6350.jpg
NBF_Tringa-brevipes_6350.jpg (87.79 KiB) Viewed 8946 times


I heard it, and although I am no expert, it was much more 'too-weet' than the "rippling trill of 6–10 notes" which I heard in Rarotonga.
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Re: Mystery Bird Quiz #1 - The Answer

Postby philbattley » Tue Aug 18, 2009 10:07 am

I'm not sure I can tell exactly where that groove ends, as the lower part is covered by water. But up close it looks rather Grey-tailed.

A general caution for tertials and primaries on waders though. There are a couple of species for which the projection of primaries can be important, but if a bird is in moult, the projection can appear longer than it would be normally. I recall this with a Pacific Golden Plover in Ghana that had dropped at least one tertial on one wing but not the other. Facing one way it looked like a Pacific, facing the other it looked like an American (of which there was one a few hundred metres away for comparison).

The tattler looks to be in moult, with just a single large tertial visible. With the projections Sav identifies then this wouldn't affect the identification, unless the bird was in primary moult and was not showing the full projection anyway. And I bet he can't disprove that proposition without more photos!

Phil
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sav
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Re: Mystery Bird Quiz #1 - The Answer

Postby sav » Tue Aug 18, 2009 2:33 pm

Hey Phil,

Apparently Visique on Broadway is a good optometrist, and handy enough to you!!

I'll admit that the original photo made the nasal groove a dubious feature, but surely the second pic from Neil is good enough to be conclusive on that.

I quite agree about caution with tertial/primary lengths. As you will see above, the primaries are evenly spaced so likely all to be there, and the single large tertial is present. I can't prove anything! I do think your original answer is quite instructive though, since I reckon you thought it really looked like a Grey-tailed and had to convince your self that it wasn't! (?)

Better luck next time mate.
Sav Saville
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Re: Mystery Bird Quiz #1 - The Answer

Postby philbattley » Tue Aug 18, 2009 11:24 pm

Hey Sav,

Thanks for the heads-up on the optometrist. I went there after work, dropped your name into the conversation, and as you are such a regular and lucrative customer there they gave me a great discount!

And yes, while better luck would be good next time, better brains would be preferable.

Phil
chambers
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Re: Mystery Bird Quiz #1 - The Answer

Postby chambers » Sat Aug 22, 2009 11:25 am

Dear contestants,

It was a good challenge. Before I made my stab at this troublesome bird I examined about 5 pictures of Wandering Tattlers taken in the islands. These birds had been photographed after hearing their musical whistles. Two of these were from Simon Fordham's collection. Although blurred in some pictures the nasal grooves were there and about the size of the bird in the quiz. Further, the white eye markings and length of wing feathers appeared about the same as Neil's picture.

However, I don't doubt the bird in the picture is a grey-tailed. I have since examined my Grey-tailed pictures taken in Australia and the bird is very similar to them too.

So what I am suggesting is there is no really significant difference between the species. It is the very different songs that separate them - and in New Zealand the Grey-tailed has been the more frequent visitor especially at Miranda. I can well remember Geoff Moon showing us slides of Tattlers and asking which species they were - and the differences. Even Sib, who was present, was stumped, because no calls went with them.

From my casual observations I always feel the Wandering Tattler is a more slender, less hunched bird.

Anyway - make the next bird easier please.

Regards

Stuart Chambers

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