Pacific or American Golden Plover in Australia (1 Viewer)

Dear fellow birders,
Today I visited a coastal rocky platform near Sydney Australia, which is popular for wader watching during high tide.

There were about 15 Pacific Golden Plovers roosting there and among them one individual was significantly drabber looking. I initially tried to avoid looking at it as it was the least attractive of all.

While I was photographing one of the Pacific Golden Plovers, this dull colour plover came into my view and my first impression was that this bird has shorter neck, shorter leg (tibia) and much plainer throat, chest and nape.

Unfortunately this is a heavily worn bird and supposedly a juvenile. Its left outermost primaries are even lost and invisible. See my attached close up photo and by extrapolating both its left and right primaries albeit some missing ones, I can argue that this bird should have at least 5 exposed primaries at each side.

Other points which I think that suggest American Golden Plover are:-
1) Although primaries are badly worn and even missing, there should be at least 5 exposed Primaries. (See my explaination in close up tail photo)
2) Shorter neck
3) Shorter upper leg (tibia) - consistant with all the PGPs beside
4) Overal very pale grey, yellow tint only on mantle and rump. White eyebrow.
5) Nape is very plain
6) Very plain throat and chest, hardly any streaks. Not even at sides of throat.

One juvenile American Golden Plover from Nova Scotia Canada posted on this forum looks very similar to the bird I say except the bird I saw is even worn (after long journey to Australia).
http://www.birdforum.net/gallery/showphoto.php?photo=35660

I also found some useful reference sites:

Consolidation of photos of AGP and PGP
http://www.birdinfo.com/A_Images_A/AmericanGolden-Plover_image.html

Field Identification of forms of Lesser Golden Plover by Dunn, Morlan and Wilds.
http://fog.ccsf.edu/~jmorlan/goldenplover2.pdf

I took many photos of this bird but seems to get its left side only. Also have typical Pacific Golden Plovers at its side for comparison.

Although I think most features suggest to American Golden Plover but there have been very very few official accepted record of American Golden Plover in Australia.

Thank you in advance on your suggestions, which supporting my claims or not.

Best regards,
Tun-Pin

Hi Tun-Pin,
First off, let me make clear the fact that my experience of the 'lesser' golden plovers is confined to 6 or so American Golden Plovers (including juveniles) and only 2 well-seen Pacifics, both of which were 'adult-types' in July/August. Therefore, I don't really have a proper feel for the extent of variation within both species.
That said, I can't help but notice that this bird is missing most of its tertials, and, if one extrapolates the possible length of the missing feathers from the bird behind it and to our right in the last pic, it is clearly possible that, after completing its moult, there would be fewer primary tips showing beyond the tertials than it would seem from the images, perhaps 2-3 tips?
Coupled with the fact that the primary projection on the far wing doesn't seem especially long, and there's something less definable about the bird that doesn't sit comfortably with my experience (albeit limited) of AGP, I can't help but wonder if this isn't just a Pacific with aberrant moult? Perhaps this bird is a 2nd-w type, or a winter adult, compared directly with juv/1st-winters? As far as I know, a juvenile type shouldn't be in primary moult anyway until about July (or June) this year (i.e. the bird's 2nd cal year), and the retained outer primaries on the right wing do seem very worn...
Regards,
Harry

I agree that it's at least a 2nd winter bird due to primary moult, and that the pp is of no use due to missing tertials. The bird still looks a bit more like an AGP to me, but I'm not an expert either. The plumage is very greyish and the crown rather uniform. It looks quite different to any of these PGPs, but on the other hand more similar to this AGP (although it's probably a 1st winter).

By the way, isn't the PGP in the background of at least the fourth pic an adult, as it appears to have two generations of wing coverts?

CAU said:

I agree that it's at least a 2nd winter bird due to primary moult, and that the pp is of no use due to missing tertials. The bird still looks a bit more like an AGP to me, but I'm not an expert either. The plumage is very greyish and the crown rather uniform. It looks quite different to any of these PGPs, but on the other hand more similar to this AGP (although it's probably a 1st winter).

By the way, isn't the PGP in the background of at least the fourth pic an adult, as it appears to have two generations of wing coverts?

Click to expand...

See what you mean about the PGP in question, should have looked harder!

With regard to the mystery bird, I wonder if it may be a 3rd cal that, for some reason, retained a more or less complete, but worn, juvenile plumage in its 2nd cal summer, and the retained outer primaries and older coverts (which both seem worn) could still be juvenile feathers, giving the bird a dull appearance (whichever species it actually is)? Of course, I have heard of that happening with vagrant '1st-summer' AGP (and have seen pics of such birds), but can PGP show the same (aberrant?) moult strategy, or would this, if it applies to the mystery bird, strengthen the case for AGP?

CAU said:

I agree that it's at least a 2nd winter bird due to primary moult, and that the pp is of no use due to missing tertials. The bird still looks a bit more like an AGP to me, but I'm not an expert either. The plumage is very greyish and the crown rather uniform. It looks quite different to any of these PGPs, but on the other hand more similar to this AGP (although it's probably a 1st winter).

By the way, isn't the PGP in the background of at least the fourth pic an adult, as it appears to have two generations of wing coverts?

Click to expand...

I would agree with these suggestions and would favour American over Pacific on structure and plumage features visible in these images. Slight caution though bearing in mind that the bird in all images is both fluffed up and relaxed and therefore automatically looks bulkier and emphasises the shorter legged appearance.

Mark

Harry Hussey said:

With regard to the mystery bird, I wonder if it may be a 3rd cal that, for some reason, retained a more or less complete, but worn, juvenile plumage in its 2nd cal summer, and the retained outer primaries and older coverts (which both seem worn) could still be juvenile feathers, giving the bird a dull appearance (whichever species it actually is)?

Click to expand...

The 3cy theory seems plausible to me due to the heavy wear of the outermost primaries, but I don't really know much about the moult of Lesser Golden Plovers.

The mantle of the subject bird possibly contains two different generations of feathers. There are lots of pretty dark feathers with very diffuse sawtoothing at the edges, and a few much browner feathers that look older. I believe that the uniformness (and lack of yellow tones) of the (possibly) newer feathers favours AGP, but I don't really know anything about variation in PGPs. Also the head pattern seems pretty consistent with AGP, compare to the description in the (very old) identification article linked in the first post.

Harry Hussey said:

retained a more or less complete, but worn, juvenile plumage in its 2nd cal summer

Click to expand...

The plovers should still moult some feathers (e.g. scapulars) in the postjuvenal moult, so they won't be in complete juv plumage from the first winter onwards. I don't know how extensive the prebreeding moult is (first summer Greater Golden Plovers and Black-bellied Plovers don't at least usually look like adults), but they retain the juvenal wing coverts and remiges. Here's a summer PGP that has very worn wings, but looks otherwise like an adult female:
http://www.tarsiger.com/gallery/index.php?pic_id=muu1112480634&lang=eng

Anyway, this is just speculation from my part, AGP is so rare in Australia that it's checked by the rarities committee, and perhaps the bird falls within the variation of PGP.

Thank you to all who gave your good feedbacks.

One thing I like to highlight is that of all the non-breeding PGP I have come across in the given example, I have not encountered any PGP with the throat and chest so much faded until there is completely devoid of dark feather, i.e. no traces of black or dark brown marking on the throat or breast as shown in the questionable bird in 2nd photo.

I repeat the link http://www.birdforum.net/gallery/sho...hp?photo=35660
See no traces of dark feather at all in this AGP.

Although not all AGP have clean throat and breast but should n't this feature can only be found in some AGP but not PGP?

Cheers,

CAU said:

The 3cy theory seems plausible to me due to the heavy wear of the outermost primaries, but I don't really know much about the moult of Lesser Golden Plovers.

The mantle of the subject bird possibly contains two different generations of feathers. There are lots of pretty dark feathers with very diffuse sawtoothing at the edges, and a few much browner feathers that look older. I believe that the uniformness (and lack of yellow tones) of the (possibly) newer feathers favours AGP, but I don't really know anything about variation in PGPs. Also the head pattern seems pretty consistent with AGP, compare to the description in the (very old) identification article linked in the first post.



The plovers should still moult some feathers (e.g. scapulars) in the postjuvenal moult, so they won't be in complete juv plumage from the first winter onwards. I don't know how extensive the prebreeding moult is (first summer Greater Golden Plovers and Black-bellied Plovers don't at least usually look like adults), but they retain the juvenal wing coverts and remiges. Here's a summer PGP that has very worn wings, but looks otherwise like an adult female:
http://www.tarsiger.com/gallery/index.php?pic_id=muu1112480634&lang=eng

Anyway, this is just speculation from my part, AGP is so rare in Australia that it's checked by the rarities committee, and perhaps the bird falls within the variation of PGP.

Click to expand...

So rare in fact, that I am aware of only one accepted record to date.

However unconfirmed sightings have occurred and the lack of observers may mean birds are overlooked. At least there's photographic evidence in this case so the rarities committee have something more than a description to peruse.

However unconfirmed sightings have occurred and the lack of observers may mean birds are overlooked

I would guess that this is very much the case!

CAU said:

I agree that it's at least a 2nd winter bird due to primary moult, and that the pp is of no use due to missing tertials. The bird still looks a bit more like an AGP to me, but I'm not an expert either. The plumage is very greyish and the crown rather uniform. It looks quite different to any of these PGPs, but on the other hand more similar to this AGP (although it's probably a 1st winter).

Click to expand...

I learnt from American Birding website
http://www.aba.org/birding/v37n5p470.pdf
that in page 472, it mentions of both forms having different moulting stategies - "... As for immature birds, Americans molt primaries in their first winter, but Pacifics do not until the following summer or autumn...."

Dear CAU, if this is a 1st winter bird and still moult its primary, could this leans towards AGP as per described in the article?

I have received few feedbacks from local australian birders that it is inconclusive to ID a heavily worn bird because the following features are nolonger reliable :-
1) # of Primary tips exposed past tertials
2) primary projection

However I am betting that the bird will hang around long enough for many other to observe and better still wait for it to have a complete moult. The site is a well known roosting site for a small number of shorebirds including Pacific Golden Plover and Red-necked Stint. Occasionally we have Wandering Tattler (a rarity but reported lately), Red Knot, Curlew Sandpiper and Bar-tailed Godwit.

I now attach the 5th photo to show its complete length of tarsus (lower leg). Quite a short legged bird by PGP standard, or probably for AGP too.

Stay tuned

Certainly looks promising!

Tunpin - could you post a few more pics please? Also, could you post one or two shots that are either uncropped or taken at a greater distance? Sometimes these can help give a better indication of how one individual bird compares to the others stood around it.

tunpin.ong said:

I learnt from American Birding website
http://www.aba.org/birding/v37n5p470.pdf
that in page 472, it mentions of both forms having different moulting stategies - "... As for immature birds, Americans molt primaries in their first winter, but Pacifics do not until the following summer or autumn...."

Dear CAU, if this is a 1st winter bird and still moult its primary, could this leans towards AGP as per described in the article?

Click to expand...

IF the bird is a 1st winter, then the primary moult indeed points towards AGP. It was news to me that they have a different moult strategy than PGPs, there are not many photos of winter AGPs on the net. However, IMHO this information actually implicates stronger that the bird is a 2nd winter PGP, due to the extremely worn outer primaries (by the way, I believe that due to symmetry reasons the primary that's labeled the 2nd from the right is actually the 1st from the left).

This is the article (by Jaramillo) the ABA article is referring to:
http://elibrary.unm.edu/sora/wb/v35n02/p0120-p0124.pdf

Here's an excerpt from it:
"Pacific Golden-Plovers may remain in the winter range during their first and sometimes second summer; these over-summering birds tend to molt into a dull alternate plumage resembling the basic plumage. But many one-year-old birds move north to the breeding grounds in their first spring, and these tend to assume a brighter alternate plumage. Surprisingly, Pacific Golden-Plovers never molt primaries during their first winter. Immatures summering in the winter range molt their wings during their first summer (July-November), whereas immatures migrating to the breeding range do so in their second autumn August-January (Johnson and Johnson 1983). Young Pacific Golden-Plovers may perform three migrations on juvenal primaries!"

Like already concluded by Harry, your bird may be a PGP that has performed three migrations on juvenal primaries, thus explaining the heavy wear of the outer unmoulted ones. As based on the article AGPs of similar age have already moulted all the primaries at least once, they would (at least probably, there can of course be some variation) be less worn. However, I stay tuned to see how the appearance of the bird changes during the winter!

CAU said:

IF the bird is a 1st winter, then the primary moult indeed points towards AGP. It was news to me that they have a different moult strategy than PGPs, there are not many photos of winter AGPs on the net. However, IMHO this information actually implicates stronger that the bird is a 2nd winter PGP, due to the extremely worn outer primaries (by the way, I believe that due to symmetry reasons the primary that's labeled the 2nd from the right is actually the 1st from the left).

Click to expand...

Agree ( P10)


[/QUOTE]Here's an excerpt from it:
"Pacific Golden-Plovers may remain in the winter range during their first and sometimes second summer; these over-summering birds tend to molt into a dull alternate plumage resembling the basic plumage. But many one-year-old birds move north to the breeding grounds in their first spring, and these tend to assume a brighter alternate plumage. Surprisingly, Pacific Golden-Plovers never molt primaries during their first winter. Immatures summering in the winter range molt their wings during their first summer (July-November), whereas immatures migrating to the breeding range do so in their second autumn August-January (Johnson and Johnson 1983). Young Pacific Golden-Plovers may perform three migrations on juvenal primaries!"[/QUOTE]

Quite a revelation!

[/QUOTE]Like already concluded by Harry, your bird may be a PGP that has performed three migrations on juvenal primaries, thus explaining the heavy wear of the outer unmoulted ones. As based on the article AGPs of similar age have already moulted all the primaries at least once, they would (at least probably, there can of course be some variation) be less worn. However, I stay tuned to see how the appearance of the bird changes during the winter![/QUOTE]

All you can do really, two voices of wisdom

I now attach the 5th photo to show its complete length of tarsus (lower leg). Quite a short legged bird by PGP standard, or probably for AGP too.

Possibly not - http://www.gos.org/sightings/24-plovers/agpl-20060322-cl.jpg

1) Dear CAU, First of all, thanks for pointing the wrong labelling of primaries and I now attach corrected photo 6 on the tertials-primaries-tail again. Pls correct me if there are still any mislabelings.

2) We have not yet established the age of the bird, have we? To be honest I am not good in aging shorebird especially Golden Plover but my impression is that juvenile is more spotty, streaky and yellowish. But this bird is so plain amd greyer. Assuming this is a full adult and it is moulting its primaries now, shouldn't it fit in the excerpt given by CAU's link http://elibrary.unm.edu/sora/wb/v35n02/p0120-p0124.pdf (Correct me in photo 6 and 7 if I am wrong that I took the darker feather as fresh primaries)

"Pg122....the molt of the Americani s significantlly later than that of the Pacific, this difference being most clear in wing molt....suggesting that the American molts its wings one to two months later than the Pacific..."

3) I found one link where a PGP and AGP were also photographed side by side in Washington State, USA. Isn't the AGP has plainer lighter throat and breast? (refer to my photo 2). AGP's Eye stripe and dark ear covert almost join together. AGP's bill is more angular and thicker at base wheres the PGP's bill is more tapered and looks "parallel".
http://scienceblogs.com/grrlscientist/2008/10/todays_mystery_bird_for_you_to_40.php
These features can also be found in attached Photo 8.

4) Dear tittletattler, I have attached more photos but there is a limit on file size. Photo 8 was taken using Canon DSLR whereas the rest were by digiscoping.

5) Dear rockfowl, suppose your short-legged Golden Plover in http://www.gos.org/sightings/24-plovers/agpl-20060322-cl.jpg
is an AGP as its filename is "agpl". This bird too has eyestripe and dark ear covert almost meet each other. Although this may not be a definate ID for AGP.

Thank you very much on your inputs so far.

tunpin.ong said:

2) We have not yet established the age of the bird, have we? To be honest I am not good in aging shorebird especially Golden Plover but my impression is that juvenile is more spotty, streaky and yellowish. But this bird is so plain amd greyer. Assuming this is a full adult and it is moulting its primaries now, shouldn't it fit in the excerpt given by CAU's link http://elibrary.unm.edu/sora/wb/v35n02/p0120-p0124.pdf (Correct me in photo 6 and 7 if I am wrong that I took the darker feather as fresh primaries)

"Pg122....the molt of the Americani s significantlly later than that of the Pacific, this difference being most clear in wing molt....suggesting that the American molts its wings one to two months later than the Pacific..."

Click to expand...

The timing of the moult fits both adult AGP and 3cy PGP, but the heavy wear of the outer primaries fits perhaps better 3cy PGP.

tunpin.ong said:

3) I found one link where a PGP and AGP were also photographed side by side in Washington State, USA. Isn't the AGP has plainer lighter throat and breast? (refer to my photo 2). AGP's Eye stripe and dark ear covert almost join together. AGP's bill is more angular and thicker at base wheres the PGP's bill is more tapered and looks "parallel".
http://scienceblogs.com/grrlscientist/2008/10/todays_mystery_bird_for_you_to_40.php
These features can also be found in attached Photo 8.

Click to expand...

You are correct regarding the shape of the bill, but both of the birds in your link are in juvenile plumage, and therefore you cannot make any too detailed plumage comparisons with the subject bird (which is not in juvenile plumage).

There are not many "Sequels" in this ID Forum and I hope many readers will find post this interesting.
On Fri 16 Jan, 5th day since I last sighted this questionable Golden Plover, I revisited the site and I could immediately tell it apart from 13 other typical Pacific Golden Plovers. This sneaky Golden Plover liked to tuck in the rock depression and hence showing its head only most of the time. I had no problem to tell it apart by its bigger head. Have I got personal aquantance with this bird? or maybe I am already familiar with the jizz of this bird.

There is not much discovery from this bird apart that its had shed all its worn outer primaries since I saw it 4 days ago (See photo 09). It is now pointless the judge a bird by its primary project at this stage.

I have also taken photos of other Pacific Golden Plovers (Photos 10), it shows some features which may be mistaken as AGP:-
1) whitish eyebrow(instead of typical yellow)
2) almost plain throat and chest (instead of streaky)
However I was able to dismiss them quickly by their strongly marked upperparts spotted with rich yellow and longer legs.

I also saw another PGP where its tertials were badly worn (saw-tooth edged) and reduced. Hence showing its fresh and nice primaries and I could counted 5 of them. (Of course with worn tertials it is not accurate to base on Primary project and more importantly I could still tell this is a PGP because of strongly marked upperparts, albeit worn).

The point I want to bring up is that adult PGP moult its feather earlier, would have completed its primary moult by now (August - December).

CAU said:

The timing of the moult fits both adult AGP and 3cy PGP, but the heavy wear of the outer primaries fits perhaps better 3cy PGP.

Click to expand...

If it is indeed an adult PGP at 3CY it should have completed its moult by now, just like the other PGPs that I saw. Unless there is particular report that 3cy moult their primary specifically later than other 4,5,6..cy PGP.

I just realise that another pitfall in photo comparison is that we should try much as possible, compare examples within the same latitude. (In the case of Nordmann's Greenshank which I am familiar with in Malaysia, can look very different when they are in Korea and Japan).

Search through the web specifically for AGP found in South America, they traditional winter ground, I think I have some more examples which looks closer to the questionable bird - plainer, browner.

Scroll down for American Golden-Plover - The photos must have been taken from different individuals
http://www.fotosaves.com.ar/Charadriiformes/FotosCharadriiformes1.html

http://www.clubdeciencias.com.ar/avesweb/Chorlo Pampa (Pluvialis dominica).JPG
http://www.cema.edu.ar/eventos/muestras/rodriguez/72.html
http://uruguay-birder.tripod.com/sitebuildercontent/sitebuilderpictures/pluvialis_dominica.jpg

Compare photo 2,3,4. I think the questionable bird look more similar to these bird from Argentina rather than the australian PGP next to him.

Really hope the bird will stay on and by the time we shall get much better answer by looking at its primary projection in completely molted feather.

Regards,

Summary of new photos - all taken on 16 Jan except Photo 09
Photo 09 - Missing outer primaries since 12 Jan
Photo 10 - PGP for comparison
Photo 12 - General Side shot, comparison with plumages matches bird photoed on 12 Jan.
Photo 13 - Rear view showing nape
Photo 14 - Another Rear view showing tertials
Photo 15 - Rear View (Compared with Typical PGP)

tunpin.ong said:

If it is indeed an adult PGP at 3CY it should have completed its moult by now, just like the other PGPs that I saw. Unless there is particular report that 3cy moult their primary specifically later than other 4,5,6..cy PGP.

Click to expand...

But there is a particular report that says that second winter (now 3cy) PGPs moult their primaries specifically later than older PGPs. You seemed to miss it, it's included already in post #12.

"Immatures summering in the winter range molt their wings during their first summer (July-November), whereas immatures migrating to the breeding range do so in their second autumn August-January."

CAU said:

But there is a particular report that says that second winter (now 3cy) PGPs moult their primaries specifically later than older PGPs. You seemed to miss it, it's included already in post #12.

"Immatures summering in the winter range molt their wings during their first summer (July-November), whereas immatures migrating to the breeding range do so in their second autumn August-January."

Click to expand...

Dear CAU, Thank for your very quick response and confirmation. The author gave the primary molt for 3cp PGP a wider period August-January as compared with older adult in more specifc period August to mid September. - So badly worn that it takes longer time to replace? :-O

With regards to the plain grey brown looking upperpart, following is a link to an unpublished memorandum on similar issues also in Australia by Tony Paliser 2002 http://users.bigpond.net.au/palliser/barc/SUMM409.htm

"...Pacific Golden Plovers can (uncommonly) have very grey looking upperparts, and this is under-rated by Palearctic literature, presumably as it is a plumage condition seen on the non-breeding grounds rather than on migration. As far as we know, locally, the basic plumage of Pacific Golden Plovers can only be so grey-looking when it is very worn. If the basic plumage seen on this bird were fresh, Pacific Golden Plover would be out of the question. But was it fresh?..."

There are certainly other PGPs within the flock that have more worn plumage but still look more strongly marked and more yellowish spotted than the questionable bird. But is this bird has plumage fresh enough to justify that? Even for a few feathers o? Or rather it is safer to treat this as a very little known aberrant form of PGP at this stage?

I still think it does look close to many AGPs in South America (the generic non-breeding type adult). On the other end of possibility, it is good also that if this questionable bird can be soon dismissed as a form of PGP that has been recorded before. So that this will add to the birders' knowledge and precaution to differentiate between a real rarity and a variety form of common bird if it turns up in this part of the world one day.

The 3rd posibility is that, based on the current literature we have, this bird's true identity will remain unknown.

tunpin.ong said:

The 3rd posibility is that, based on the current literature we have, this bird's true identity will remain unknown.

Click to expand...

Possibly.

Can you get some more shots please? Different angles, distances etc.

tittletattler said:

Possibly.

Can you get some more shots please? Different angles, distances etc.

Click to expand...

Dear tittletattler, I do not have many photos of different angles. I attached 2 more photos showing close up of scapulars. The other photo is a typical PGP for comparison. Both birds have about the same degree of worn scapulars. Note the broader white/yellow edging in PGP that make PGP look more spotted.

Interesting also that the questionable Golden Plover has rich yellow spotted rump (Refer to attached photo17, photo06 Post#14 or photo09 post#16) . This might be worthwhile to look into. I have found a few photos of AGP in dull greyish in constrast with rich yellow spotted rump. (Ideally I would like to choose birds photograpned in South America but I could not find any)

Juv AGP - Idaho, USA by K Carlson
http://www.flickr.com/photos/birddog/1397527261/sizes/o/

Possibly Juv AGP - Dominican Republic
http://www.flickr.com/photos/11949140@N07/2912627139/

AGP in Acores
http://www.flickr.com/photos/carlosbettencourt/3028550554/

Juv AGP in UK (2nd row left pic. A standing wing raising bird. Suppose 2 other photos photographed by same photographer on same date was a same bird, then this dull grey bird has very contrasting yellow spotted rump)
http://www.birdwatch.co.uk/website/component/option,com_zoom/Itemid,130/catid,36/

The PGP do have similar rump also but the colour does not differ significantly from other upperparts of body especially in back and mantle. Here are few examples

PGP in flight, Singapore
http://flickr.com/photos/lonesomecrow/2201184287/sizes/o/
PGP in flight, Hawaii
http://flickr.com/photos/hearman/84677250/

In the case of badly worn PGP, the bird becomes greyish overall, and so is the rump!! see examples given:-

Worn PGP in Cyprus (bottom right photo)
http://www.birdwatch.co.uk/website/component/option,com_zoom/Itemid,130/catid,36/PageNo,2/

A link posted by CAU earlier on a badly worn bird in breeding ground. Its rump is also very dull concealed under tertials.
http://www.tarsiger.com/gallery/index.php?pic_id=muu1112480634&lang=eng

I wonder if the rump has been in any literature in the past.
I follow loosely on non breeding plumage AGP regardless of age, location, but are the above examples of rump comparasions give any clues at all?