Lesser Sand Plover - proposed split

Discussion about the evolution, relationships, and naming of New Zealand birds
Ian Southey
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Re: Lesser Sand Plover - proposed split

Postby Ian Southey » Fri Feb 18, 2022 8:42 am

The Miranda bird was identified first in non-breeding plumage as a Mongolian Dotterel rather than a Lesser Sand Plover because the tail was darker than the rump. In breeding plumage it had a rich brown back and thick black lines around the mask making stegmani rather than mongolus which has a greyer back and a less well defined edge to the face mask. I should also have checked the bill length to depth ratio but didn't averages 3.33 in stegmani and 3.52 in mongolus - from HANZAB. I found pictures taken at Broome showed greyer backed birds which is how I calibrated the colour.

When I was researching this I saw somewhere (I think) that stegmani sometimes have a fully black mask but I can't find the source for that now. I thought that would account for the record of Lesser Sand Plover from the Kaipara but having now re-read the description of that https://www.birdsnz.org.nz/wp-content/u ... _2_125.pdf that seems to have been a mistake. Sorry.

Ian
gmckinlay
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Re: Lesser Sand Plover - proposed split

Postby gmckinlay » Fri Feb 18, 2022 3:44 pm

Thanks Ian,

I was not aware of the different coloration of the back. Are you able to direct me to any photos? I have Hirschfeld et ^Identification of sand plovers . Fig 9 compares facial features on stegmani and mongolus well, but not the back (or flanks) which are mentioned as different in the text.

Maybe really good side on photos might allow calculation of the bill length/depth. A matter of the birds letting me get close enough.
Ian Southey
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Re: Lesser Sand Plover - proposed split

Postby Ian Southey » Fri Feb 18, 2022 5:03 pm

Glen

Actually there's a bit of a range. Not sure how much lighting and exact stage of moult figure into it. The Miranda was pretty clearly at the richer warm brown end and not a bit like paler greyer end of the scale and also had thick black lines on the face mask. As I understand it the western Australian birds seem to be mainly mongolus and the eastern ones stegmani but I don't know how they meet around the top.

You probably don't want to rely on any single character but even if each is a bit difficult to assess you could have some confidence when they all line up. If you aren't likely to take many good pictures gather up a series of photos online and from books and work out a score you can use in the field for each bird you see well. If you're paying attention you may find other features that help. Also, have you seen this https://birdingfrontiers.wordpress.com/ ... d-plovers/. I couldn't find a link to the whole paper but this is probably the best bit.

Out east I'd expect your birds to be predominantly or all stegmani given what I have seen about staging sites but you never know,

Ian
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Michael Szabo
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Re: Lesser Sand Plover - proposed split

Postby Michael Szabo » Fri Feb 18, 2022 7:34 pm

If anyone has "Birds of the Indonesian Archipelago" (2nd ed 2021 James A. Eaton, Bas van Balen, Nick W. Brickle, Frank E. Rheindt) it would be useful to take a photo of the relevant plate/page to post to this group.
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gmckinlay
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Re: Lesser Sand Plover - proposed split

Postby gmckinlay » Sun Feb 20, 2022 12:40 am

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gmckinlay
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Re: Lesser Sand Plover - proposed split

Postby gmckinlay » Sun Feb 20, 2022 12:41 am

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Ian Southey
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Re: Lesser Sand Plover - proposed split

Postby Ian Southey » Sun Feb 20, 2022 8:15 am

I'd lean heavily toward stegmani for these birds, They have a fairly rich brown back, thick margins to their foreheads and a rough measurement of the bill gave a ratio of 3.18 (edges not super clear).

Looking here https://nzbirdsonline.org.nz/species/lesser-sand-plover I'd say breeding plumage birds from Korea and Broome are mongolus. The Broome birds is fairly brown backed but the light is very early or late and would make all of the colours warmer but the black lines on the forehead are narrow. The breeding birds from Chukotka and Queensland seem to be stegmani.

Just note that I've paid a bit of attention to this but have not the experience to be certain.

Ian
Bobolink
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Re: Lesser Sand Plover - proposed split

Postby Bobolink » Sun Feb 20, 2022 9:29 pm

Attached is a screenshot of the Indonesian Archipalago page, just the text. As you can see Siberian Plover has two subspecies: mongolus and stegmanni, and Tibetan Plover has three subspecies: atrifrons, schaeferi and pamirensis.
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gmckinlay
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Re: Lesser Sand Plover - proposed split

Postby gmckinlay » Mon Feb 21, 2022 1:09 pm

Thank you very much Ian. You have given me enough info to conclude it should be possible to nail this subspecies puzzle down - I had sort of put this in the too hard basket for several years. The breeding plumage males look to be reasonably straightforward. Additionally, if I can get a good number of quality photos, that could allow the bill ratios to be estimated, even when birds are not in breeding plumage. There seems to be a peak in the lesser sandplover numbers near the end of March and the end of September. I will aim to cover both those periods this year.

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