Possible American Golden Plover on Codfish

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sav
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Possible American Golden Plover on Codfish

Postby sav » Wed Oct 24, 2018 6:07 pm

Hey all,

Check out Johannes Fischer's photo of a Golden Plover sp on Codfish Island. It is wholly grey toned and has 4 well-spaced primary tips visible past the tertials. I can't see the tail v wing tips, but it looks long at the rear end to me.

The photo is on New Zealand Birders Facebook page https://www.facebook.com/groups/857726274293085/

cheers
Sav Saville
Wrybill Birding Tours, NZ
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Davidthomas
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Re: Possible American Golden Plover on Codfish

Postby Davidthomas » Wed Oct 24, 2018 7:40 pm

Photos courtesy of Johannes Fischer.
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RussCannings
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Re: Possible American Golden Plover on Codfish

Postby RussCannings » Wed Oct 24, 2018 8:49 pm

Being a drab golden plover with long-looking primaries (and being on Codfish) makes this bird ripe for raised eye-brows. Indeed it caused some excited discussion behind the scenes earlier today. I hate to seem like I'm "Anti-American" after the Ellesmere bird (last summer? or the one before that?), but I think this is another one of these drab juvenile Pacifics with worn tertials that has the superficial appearance of a Yank.

Here's why I think it's a Pacific:
-Ill-defined greyish supercilium that narrows above and in front of the eye
-Prominent dark auricular patch
-Wonky-shaped head (No offence Pacifics but Americans are just cuter and more evenly proportioned in the head/bill department)
-Tail is not well defined in these photos but Photo #2-3 possibly show it and makes it seem like there is little (if any primary projection). Johannes told me via Facebook chat that the primary projection appeared minimal in the field.
-While the resolution is certainly not ideal, I count only 3 primaries that are safely projecting beyond the longest tertial (Best seen in the final 2 photos). And even if the 4th barely projects, the tertials (to my eye) look distinctly worn (Which is to be expected at this time of year, and after a long flight especially with a drab bird--indicating wear--even for American juveniles).
-Juveniles (which I believe this bird to be regardless of species) have shorter tertials so the primaries always look a littler pointier and thus extra caution is needed. Add wear/moult to this (Not sure of the tail situation?) and it's a recipe for over-selling the primary projection. **That being said, there could be a hidden outer primary close to the tip that is not visible in these photos (Which can happen)**. Johannes seemed to indicate though that this was not the case.
-Tibia appears relatively long
-Pacific is the most likely option and juveniles are often quite grey at this time of year (We seem to discuss candidates every Oct/Nov no?)

So in sum, everyone is absolutely right to raise flags on birds like this--and I hope that regardless of one's opinion on this bird, everyone will pay extra close attention to the next group of golden plovers they see. The synopsis above is my perspective--but I'm always open to being convinced otherwise or for people to simply ignore me :D

Russ C
Morrinsville, NZ
(Now a proud Dad! ... though looking at less plovers these days ;) )
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sav
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Re: Possible American Golden Plover on Codfish

Postby sav » Thu Oct 25, 2018 1:27 pm

Hey Russ,

You may well be right, but I wonder about some aspects of the argument.......

Here are a few questions,

Why do we get grey-toned PGPs here when they dont appear to be anywhere else? (Hawaii, Fiji etc)

There are certainly 4 primary tips visible in the photos. Why would the tertials wear at a different rate to other feathers? (and they show no signs of wear to me anyway). I can understand previous cautions surrounding shed tertials, but worn to a frazzle??

Does the stance, body condition, temperature have any bearing when looking at tibia length.

I see that Johannes has heard it call and it called like a PGP. Which to me means it called quite like an AGP too!!

cheers
Sav Saville
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RussCannings
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Re: Possible American Golden Plover on Codfish

Postby RussCannings » Thu Oct 25, 2018 10:58 pm

Hi Sav,

I'll do my best to (partially?) address your questions. I should also perhaps re-qualify my earlier assessment as an opinion based on available evidence rather than an absolute identification. As always, open to new ideas and higher rez photos!

1) The only Pacific island I've ever birder (other than NZ) is Samoa and that was in July when there were only a few PGPs kicking around and all were in ratty basic plumage--so cannot really comment on the frequency of greyish juveniles turning up in Oct/Nov. I did a quick google search but very few juveniles seem to come up. Perhaps worth checking into this further. Australia does seem to get similar birds (and the new field guide has a "worn" juvenile picture from "Oct-Nov"). My best guesses in terms of answering your question is that a) Unless you bird Hawaii/Fiji in this window (prior to December pre-basic moult) you wouldn't notice juveniles like this, and/or b) NZ/Oz birds might be a bit more worn overall due to a longer journey?

2) I agree that 4 primary tips are visible but to me (the last 2 photos above seem easiest to judge) the shortest one is even with or shorter than the longest tertial--so given that tertials are typically shorter/frayed in juvs (I admit this is not an easy thing to confidently judge in these photos) I am not convinced it's American enough. To your question about different wear rates of feathers, I believe this is a relatively normal thing for this species. Firstly primaries are the most important flight feathers so are generally sturdier than coverts/tertials etc and I have been told in the past that black outer primaries are particularly durable (e.g. That's why most gulls have black primary tips). Juvenile Pacific Golden Plovers retain their juvenile primaries (I believe) all the way through to the following year while undergoing a complete moult of body feathers and coverts. So by the time Jan/Feb roles around, they look just like non-breeding adults but (upon close inspection) with older primaries. In lieu of better shots of the Codfish bird, check out the Ellesmere bird from a couple seasons ago which Mike Ashbee brilliantly photographed (viewtopic.php?f=9&t=6273&hilit=american+golden). Scroll down to the close up of the primary projection and note the distinctly frayed tertials that are down to spikes. Also note that these spikes project to or beyond the 4th longest primary. I don't think the Codfish bird has quite this degree of wear but it's probably on the spectrum.

To add to this, here are photos I took of 2 different Miranda juveniles in November last year. Note the general wear of the coverts (and resulting drabness) compared to the relatively crisp-looking primaries.
PGP1.jpg
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PGP2.jpg
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3) I would say that the factors you listed would definitely impact an observer's perception of tibia length. I only mention it as a single aspect of a bigger picture. In general Americans are less leggy (and this is noticeable when looking at a wide selection online), but this should never be used as a "clincher" per se (unless you actually measured it).

4) Agree that calls can be tricky depending on what call it is and one's experience. I'd have to let Johannes clarify that one but in general I find typical wintering ground (NZ) Pacific calls to be the distinctly disyllabic calls (very similar to Semipalmated Plover) that are fairly distinct from American (but again--you wouldn't want to use JUST this aspect).

Russ
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sav
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Re: Possible American Golden Plover on Codfish

Postby sav » Sun Oct 28, 2018 12:01 pm

Hey all,

Just to add some more to the discussion. What about this bird? Which I think has a large bill and long legs....

http://www.surfbirds.com/gallery/share_ ... 227364.jpg

Still confused....
Sav Saville
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Re: Possible American Golden Plover on Codfish

Postby RussCannings » Sun Oct 28, 2018 12:25 pm

I hear ya,

Agree that this single angle perhaps gives the head/bill more of a Pacific look and the legs are on uneven ground so a little tricky too. As always, I would prefer a variety of angles and postures to feel comfortable about rare birds but having said that--

In this case the 4th longest primary is UNQUESTIONABLY well beyond the longest tertial (Which shows no abrasion), and the eye-brow/supercilium remains relatively consistently broad in front and beyond the eye (more even and conspicuous, even in a somewhat washed out bird like this).

I think the hindneck pattern (i.e. Shape of spots etc) can be used as well (Especially in such a great photo like this) but that is beyond my current knowledge and I don't have time to do any homework at the moment...

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