Mystery Bird #2 - The Answer

Monthly challenge to test and improve your bird identification skills.
User avatar
sav
Posts: 697
Joined: Fri Jul 03, 2009 9:49 am
Location: Havelock North
Contact:

Mystery Bird #2 - The Answer

Postby sav » Sun Aug 15, 2010 1:04 pm

Although this was more-or-less a portrait of the subject bird it was by no means an easy task, and to be honest the answer may not satisfy all of you!! I believe it illustrates the difficulty surrounding the identification of Charadrius plovers.

I'll start with the slightly "easier " wrong answers:
It's not a Shore Plover, due to general structure, green/grey legs, bill length and shape.
It's not a Banded Dotterel either. It lacks the warmth of brown (and buff) that a Bandie would show, and the bill is far too big.
Nor is it a New Zealand Dotterel. There are several fairly subtle reasons why not - including the long and thin legs, the shape of the bill (the lower mandible should curve upwards at the tip), the facial pattern, the lack of white edging to the mantle feathers, and the general shape just isn't "dumpy" enough.

So it sort of has to be either a Mongolian Plover (Lesser Sand Plover) or a Greater Sand Plover (Large Sand Dotterel), and that's where it starts to get really tricky!!
We are lucky that we only get the eastern races of both here - effectively the biggest GSPs and smallest Mongolians :in Europe it is way harder, where the opposite is true.

If one were able to compare the size of this bird with anything else I guess it would be patently obvious which species it is, but no such luck. So how to attack the problem? I reckon that first impressions are valuable: this bird looks large billed and it's legs look long and thin (and pale?) to me. The legs are really important - GSP often looks like it's legs are out of proportion to the body size, Mongolian looks much more "normal" (very much like a Banded Dotterel in structure). Mongolian Dotterel legs are usually grey, while GSP usually has paler greenish legs.
Bill structure is another good clue - Mongolian smaller and with a faintly bulbous tip, GSP longer and more tapered.

Anyway - it IS a Greater Sand Plover, photographed by Neil at Miranda in March. Those features mentioned above are all rather subjective, and if you were one of many that picked Mongolian I wouldnt be too sad - two things that are "wrong" for GSP are apparent in the photo. Namely, it doesnt show the normal horizontal stance, nor the flatter, squarer head of a GSP. Maybe the very best clue wasn't available until now........Igor went for GSP!!

So, it WAS hard. Thanks to all who participated - 12 out of 29 entries were correct.
Sav Saville
Wrybill Birding Tours, NZ
Great Birds, Real Birders
User avatar
Peter Frost
Posts: 171
Joined: Sun Jul 05, 2009 9:59 am

Re: Mystery Bird #2 - The Answer

Postby Peter Frost » Mon Aug 16, 2010 12:29 pm

"B****r", as Telecom's boss said while trying to convince us that you can get XT reception on the Greenstone.

Could Neil share some more photos with us, so that we can see the bird in other lights and postures, and especially alongside some other species, so that we can judge its size.

I must admit that I still have a lingering doubt (sorry Igor, your status as the final arbiter notwithstanding ;) ). Having recently seen GSP at Merta Sari in Bali, one of the characteristic features to me was the apparently long tibia of the GSP, relative to its tarsus. As a result, the "knee" appears about half way down the leg, whereas in Mongolian Dotterel, it appears only about a third of the way down. I think that it is this feature that appears to give the GSP its long-legged appearance. Because of this, which the ID Quiz bird didn't show, I discounted the relatively large bill (convincing myself that the bird I saw in Bali had a larger bill that showed a more pronounced bulge at the end). This is the only thing that looks about right for GSP (judging leg colour on photographs is dicey, I think); all the rest -- rounded head, a normal-sized eye (GSP eyes look large), large tibia:tarsus ratio -- scream "Mongolian". I guess the lesson is: Don't focus too much on one character. "B****r!" :cry:

Peter
User avatar
Neil Fitzgerald
Site Admin
Posts: 3335
Joined: Mon May 18, 2009 10:20 am
Location: Hamilton, New Zealand
Contact:

Re: Mystery Bird #2 - The Answer

Postby Neil Fitzgerald » Tue Aug 17, 2010 3:18 pm

I'm sorry, but I have only the one photo. I only considered it a record shot.
It was March 2007, and it almost certainly is the individual that Phil had seen there (Miranda) at that time.
User avatar
Shane McPherson
Posts: 128
Joined: Fri Jul 03, 2009 10:01 am

Re: Mystery Bird #2 - The Answer

Postby Shane McPherson » Tue Aug 17, 2010 8:28 pm

well thats unfortunate! but some good lessons to be learnt.

FYI the features I took were along similar lines. For one I wouldve expected the knee to be proportionately closer to the ground. The other feature I took, probably quite naievely, as that, given the bird was in reasonable profile, the bill length was estimated using the proportional length of the head, where I believed the Mongolian bill to be only as long as the gape to the eye (half head length), where GSP longer.

At about the day the quiz closed I had a catchup with Tony H about our Tapora monitoring, and we eventually got onto the topic of sand plover (i tried to delicately lead him to describing the main hurdles ;). While I am following eBird and B-NZ reports from Tapora regularly it is interesting that the species seem to switch back and forth frequently depending on who was last birding there, one week its 2 Mongolians, the next its 2 GSP's, and a week later Mongolians are back again.

This is evidently one of the most trickiest separations to make. Epic fail... now im one down :(
User avatar
sav
Posts: 697
Joined: Fri Jul 03, 2009 9:49 am
Location: Havelock North
Contact:

Re: Mystery Bird #2 - The Answer

Postby sav » Tue Aug 17, 2010 9:30 pm

I think I should add a couple of thoughts. I know that the photo isn't a very convincing Greater Sand Plover, but I am quite certain that it is one. I wholly understand the frustration of both Peter and Shane (and probably some others) who make good points, but to me it just can't be a Mongolian Dotterel - and I can't totally put my finger on why...

I think we might all benefit from some more expert opinion if anyone is keen? Shane's comments regarding the difficulties of separation of these 2 species are very apt. I'm pretty sure that both are erroneously reported quite a bit, not only confused with each other, but also NZ Dot for Greater Sand Plover and Banded for Mongolian. I know I have made that last mistake quite recently myself, as Phil Hammond will testify!
Sav Saville
Wrybill Birding Tours, NZ
Great Birds, Real Birders
User avatar
Peter Frost
Posts: 171
Joined: Sun Jul 05, 2009 9:59 am

Re: Mystery Bird #2 - The Answer

Postby Peter Frost » Wed Aug 18, 2010 12:14 pm

How about sending the photo to Erik Hirschfeld (editor@theworldsrarest.com), Kees Roselaar (C.S.Roselaar@uva.nl), and/or Hadoram Shirihai (albatross_shirihai@hotmail.com), and ask for their opinion(s)? See their paper in British Birds, 'Identification, taxonomy and distribution of Greater and Lesser Sand Plovers', British Birds 93:162-189, April 2000 (a pdf of the article can be downloaded from http://www.californiabirds.org/members/SandPlover.pdf). I found this article while trying to sort out my Bali bird, and I found it a useful and apparently thorough study of the identification problems posed by these two species.

In suggesting this, I'm not trying to overturn Sav's decision on the identify of the Quiz bird, if that is what it comes to. I'm happy to accept that decision in the spirit in which it was made. But just as Sav says that he can't wholly put his finger on why it is a GSP, I can't shake off that feeling of uncertainty. Getting further clarity on this, if possible, would be educational for all of us.

Peter
Jan
Posts: 1403
Joined: Fri Jul 03, 2009 10:43 am
Location: Christchurch

Re: Mystery Bird #2 - The Answer

Postby Jan » Wed Aug 18, 2010 4:11 pm

This is a fascinating discussion but how about someone posting some pics of NZ Dotts in winter plumage for S Is birders like me who have hardly ever seen one? They don't figure in those lovely wader books that show photos of heaps of Northern hemisphere birds. The only NZ Dott. I saw close up was from the window of a plane taxi-ing at Auckland airport. And some far-away ones when approaching Tiritiri, from the ferry.

Oh and how about a mystery bird that S Islanders might have seen sometimes? Long-toed Stint, Stilt Sandpiper etc!
User avatar
tim
Posts: 378
Joined: Sat May 15, 2010 7:16 pm
Location: Napier, Hawke's Bay
Contact:

Re: Mystery Bird #2 - The Answer

Postby tim » Thu Aug 19, 2010 6:58 am

Hi Jan,
A earlier forum in bird sightings with a post by christopher shows good example of non breeding winter NZ Dotterel.
Seen below viewtopic.php?f=9&t=634
Tim Rumble
User avatar
philbattley
Posts: 526
Joined: Wed May 20, 2009 2:21 pm

Re: Mystery Bird #2 - The Answer

Postby philbattley » Thu Aug 19, 2010 1:58 pm

Time to weigh in. (1) The birds in question was a Greater Sand, no doubt. (2) The lack of tibia is an illusion caused by its belly feathering not being sleek. (3) I photographed the same bird a few weeks later than Neil did and the photos below show it on its own, and with a rather plump NZD in the background. The birds on its own screams "GSP", while the one with the NZD in the back shows how different a bird can look with a different stance.

Having said that, I have also seen sand plovers in NZ that I would not want to have to stake a claim on, and also suspect that some birds switch between species when seen on different days by different observers.

Cheers, Phil
GSPNZD_IMG_0691 copy.jpg
GSPNZD_IMG_0691 copy.jpg (180.6 KiB) Viewed 8750 times
GSP_IMG_0709 copy.jpg
GSP_IMG_0709 copy.jpg (194.19 KiB) Viewed 8750 times
Last edited by philbattley on Fri Aug 20, 2010 9:51 am, edited 1 time in total.
Jan
Posts: 1403
Joined: Fri Jul 03, 2009 10:43 am
Location: Christchurch

Re: Mystery Bird #2 - The Answer

Postby Jan » Thu Aug 19, 2010 3:30 pm

Thanks Tim. Yes I remember the posting by Chris, who has visited Christchurch, hi Chris.
His pic is very like the Mystery bird one, but I see the differences, subtle though they are,
that Sav mentions.
NZ Dott. has what humans would regard as an 'overshot jaw', where the top mandible is longer
than the bottom. It also has white margins to the feathers all over the mantle, not just the 'whatever they
were called' that the GSP had.
The facial pattern is different, but so subtley that it is hard to pin it down.
The legs are stockier and just not as long, though the lack of a long tibia in the mystery bird is a puzzle.
It must be how it is standing.
Also the Dott. seems dumpy, compared to the GSP.

I have seen both GSP and LSP in OZ. But they don't seem to come to Canterbury much nowadays. Sign of the times,
I'm afraid.

Thanks v much for posting my Qs,
Jan

Return to “Mystery Bird ID Quiz”