There is a trend of birds showing up during June and August, with a few records in April, May and December. The December record is a wacky one from Newfoundland, though there are others from Florida in the winter (more expected there though). July/August seems like the most likely time for an Ontario sighting to me... and to make things a bit easier there aren't a ton of AMGP around then either.
It's been suggested that the east coast birds are mirror image orienting, meaning they migrate 80-160° in the wrong direction. As you can see above, almost all of the records are close to the Atlanta. This could be because the plovers book it across the continent and stop only when they hit the ocean? Or maybe just due to the lack of good habitat. A lot of shorebirds will fuel up on breeding grounds, then migrate a very long distance before setting down again (why Ontario gets very low numbers of almost all shorebird species, they fly over but just don't land). Some of the PAGP that breed in Alaska migrate 2000km nonstop to wintering grounds on islands in the Pacific Ocean, so the eastern records make sense if you picture the map flipping and the birds heading east instead. Anyway with all of our sewage lagoons, farm fields and Great Lake shorelines, we should have more of a chance to get a PAGP than some of the surrounding states. Unlike AMGP that are often see in fields and areas lacking any water, Pacifics seem to prefer to forage along shorelines and in wet areas.
-Identification.
Ideally we could get a definitive alternate (breeding plumage) male in prime light, with an AMGP right beside it for good comparison. This is unlikely to happen though and we will likely get a or a juvenile or ratty adult in prebasic plumage. After a lot of reading on the subject, I've narrowed it down to a few useful field marks.
1) Primary/Tertial ratio
- On the folded wing of a Pacific Golden-plover (PAGP) 2-3 primaries usually extend beyond the longest tertial, while on American (AMGP) 4-5 primaries are usually visible. I say "usually" because molt and viewing conditions can make this hard to judge. Americans have relativity short tertials and long primaries, while Pacifics have long tertials and shorter primaries. This sounds like it should be pretty reliable and, while it's a good feature at time, it may also be one of the most problematic. Almost any plover can be molting it's tertials and primaries, which means that the ratio could be thrown off/fit the wrong species. It can work well as a supporting feature though, and may be helpful in the final identification.
2) Primary projection past tail
- On a similar note, the primaries usually do not extend past the tail on PAGP, whereas they normally extend past the tail on AMGP (or are at least even with it)... extension being 0-9mm in PAGP and 12-22mm in AMGP. The long wings of American often gives the tail a scissor-like vibe.
3) Toes
- This is an iffy field mark, but I thought I'd mention it. On a flying Pacific, the toes *should* extend past the tail, where they fall short on an American. Looking at photos it seems to work sometimes.. but can be quite deceiving depending on angle/what the bird is doing. Having flight shots never hurts though!
4) White line on flanks/side of breast
- For use on adult alternate/Prebasic plumaged birds. On PAGP, there is a continuous white line from the head to the tail. On AMGP the white ends abruptly at the flanks, which are totally black. Female Pacifics have a less defined breast than males and the breast can be covered in white splotchy areas. Males have a solid black breast with a well defined white line along the side.
5) Tibia
- on Pacific, the tibia (upper leg) usually isn't feathered as heavily as American, which gives it a long-legged appearance. PAGP tends to have a longer tarsus than American, with the tibia more exposed and less feathered proximally, giving it a somewhat longer-legged appearance than AMGP. This is true in all plumages.
6) Bill
- The bill on PAGP is almost always longer and thicker than that of American, which appears more obviously when the birds are side by side. Looking through photos this seems to hold up quite well!
7) Golden Speckling/Overall Vibe
Adult Pacific's tend to have more, and larger golden spots on their back than American's do, and while in preformative molt there often seems to be a lot of messy white splotching throughout (not really seen on AGPL). In Prebasic plumage, PAGP often show a more buffy face as well. As for the impression the bird gives, or the "vibe", this is tough for me to write about as I've never seen one in real life. Reading accounts from other people/looking at photos and videos, PAGP usually have lankier and taller impression than AGPL, with a rounder head. I'll update this when I see some in the future : )
Let's have a look at bird pictured below. It's a fairly bright and well defined plover in definitive alternate plumage, with a white line extending unbroken from the head to the undertail coverts. Three primaries are visible past the longest tertial and the primary projection seems to be pretty short (tough to judge from one shot sometimes though).
- Pacific Golden-Plover
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Things to note: - short primary extension past tail/long tertials
- white along flanks
- long tibia due to lack of feathering
- large, thick bill
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Quick sidenote. I used pictures from the Macaulay Library for this post, however the resolution will appear poor because they are screenshots. To see the full quality images/photographer info, click the links below the photos.
Now this adult American. It's a pretty straight forward ID as far as plovers go... white ending sharply above the beast, all dark flanks and undertail coverts, 5 primaries visible past the longest tertial. Primaries extend beyond tail, short tibia due to feathering.
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Things to note - - long primary extension past tail/short tertials
- white limited to upperparts, dark flanks/undertail
- lots of feathers around tibia
- Shorter, thinner bill
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Juvenile birds
- Juvenile Pacifics usually appear buffy golden overall, where American is more gray and dull in comparison. This seems to hold up among most juveniles, though it becomes increasingly less obvious into late fall, when the feathers become worn and more grey. Juveniles gain their first plumage on breeding grounds in the tundra, then begin a preformative molt once they reach their wintering range. Juvenile plumage is mainly visible July through October, though sometimes all the way into November. PAGP also lack the very prominent white supercilium shown by AMGP, instead showing a golden wash through the supercilium and face. This golden yellow look gives pacific a very warm and buffy appearance. Most birds lack vibrant golden tones by November, though some is retained on the head and scapulars.
- The primary formula mentioned for adults (3 Ps visible past longest tertial) can still be used on juvenile birds, although molt effects this heavily. This is somewhere where APGL differs from PAGP, as American is the only Pluvialis plover that includes all of it's primaries during preformative molt in the fall... Which could potentially create confusion and give a bird a "shorter winged" look. Keep in mind that most Americans molt later when they reach wintering grounds, however preformative molt could start as early as mid/late October. Because of this difference in molt timing, it stands to reason that in the spring birds with fresh primaries should be AMGP, while birds with old primaries should be PAGP (which don't molt flight feathers until after their first summer). There can definitely be tricky birds during this time, so careful documentation is required.
- Something else I found while researching different articles/videos was that juvenile Pacific head shape differs from that of American. The head of an American looks more capped and squared off than that of a Pacific, also American often has a thinner nape line. I went through a lot of photos on Macaulay Library, and this does hold up quite well. There are Pacifics that appear capped, but if you look at that, the bill, and the buffiness of the face together, it's often quite reliable!
Ok, with all that said, lets have a look at some photos!
First up is this juvenile bird from Washington, US. It is very buffy overall, with an off-white, sort of golden supercilium. It also shows a long bill, long tertials (3 primaries visible past tertials) and the primary projection past the tail is quite short. Additionally, the cap isn't that dark/prominent and there isn't much coarse streaking. All told a pretty solid pacific!
For comparison, here's a photo of a juvenile bird from here in Ontario. Compared to the PAGP above, it is very grey overall, with a bold white supercilium and a shorter bill. The face is very stark grey and white, lacking the buffy golden tones. Similarly the rest of the bird's plumage is very grey overall, as seems to be the case with a lot of young AMGP. The long primaries are clearly visible, with 4 projecting past the tertials and going well past the tail.
Here's an AMGP from Toronto, clearly showing a long primary projection/extension past tertials, a white supercilium and a strong capped look to the head (dark crown contrasting strongly with nape).
This photo from Alberta shows an AMGP that is quite buffy overall, with a fairly nondescript supercilium and a pretty golden speckled back. Note the strongly marked, dark cap, short bill and long primary extension past tertials. Also, even though the face is quite dark and messy overall, it still has more of a "cold" grey look to it.
To show an extreme side of things, check out this juv PAGP from Alaska. This birds entire body is very golden, from it's head all the way down to it's face. Hardly any white or grey visible in the face, just a yellowish wash. Short primary extension past tertials also visible. This bird does have a bit of a capped appearance, though it's not as stark/obvious as it is in most AMGP.
Next up is this adult bird, one of the East Coast from North Carolina. It was taken in August and the bird is clearly in the middle of heavy molt, with some of the body feathers, scapulars and tertials appearing very worn and ratty. It's tough to use the primary/tertial ratio on this bird, though the primaries still appear to not project very far past the tail. This bird clearly has a very large bill, and there is white visible all along the edge of the flanks/undertail coverts. Limited feathering visible on the tibia as well.
Most of the Eastern records are either adults in July and August, or juveniles later in the season. The adults tend to be quite worn and messy, though most aren't that big of an ID challenge if you know what to look for. Here's another adult, this one from Massachusetts in late July. Face very white with large bill... lots of white on the flanks/undertail coverts, very large golden speckling on the back, short primary projection past the tail. If you click the eBird list after viewing the photo, the finder has some thorough comments about the sighting which are cool to read!
Something interesting I found while going through photos... the old world PAGP appear a lot more golden in juvenile plumage. Like this bird for example..
Another interesting thing to note.. especially later in the season (Nov/Dec), some juveniles are quite worn and seem to totally lose their golden colouration.. like this bird..
It's worth noting that I didn't discuss adult birds in full basic plumage at length. This is the most unlikely plumage to show up in Ontario, so I mainly focused on the ones that pertain to the majority of the Eastern ABA records (juvs and summer/early fall adults). Identifying an adult in basic isn't too much different from a juvenile bird though, as most of the field marks mentioned will still hold up! There is also the possibility of a 1st/2nd alternate showing up during the spring, but again I wanted to keep this fairly short and focus on the most likely plumages.
- ConclusionI have a few takeaways from searching through a lot of Golden-Plover photos are articles. The main one is that most features are variable, and if you're trying to identify a bird based entirely on one thing it may result in misidentifications: for example, assuming a very dull grey bird is always an American, or relying on the primary ratio and not taking molt into consideration). A few ID marks hold up quite well... I found the very stark, "capped off" look of juvenile American Golden-Plovers is found on almost all birds, though sometimes Pacifics can show a bit of a cap too. It can definitely be a starting point though, like any of the ID marks mentioned above. The primary extension/primary to tertial ratio is also very helpful, though not without it's faults (molt, viewing conditions). If all the features start lining up though, it's likely that you have a bird worth investigating further! Americans that are very buffy/golden usually will display at least one or two characteristics of it's species, while the same can be said for a dull pacific with a smaller bill.
Study a bird that seems even a bit "off"... look very closely at the entire bird, and try to take good notes describing everything you see/document it well with photographs. Careful observation of any Golden-Plover you come across will be helpful, as once a good familiarity is established with Americans it will be a lot easier to notice when something looks different. Some distant birds simply aren't IDable too... and it's ok to leave a bird as a "sp" sometimes...
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