Thursday, August 23, 2018

Common Ringed Plover in North America: Records, Analysis and Identification: Part l

The purpose of this article is simple. It is meant to be a thorough discussion of the presence of Common Ringed Plover in North America. I will examine all the records for the species of North America, discuss trends in vagrancy for the species; and I will examine the identification of Common Ringed Plover in detail. I will examine a number of unusual individuals of both Common Ringed and Semipalmated Plover in an effort to find the best and most consistent means of separating these two species in all plumages.

While this article is intended for North American birders identifying Common Ringed Plover, it will certainly also be of use to European birders who are seeking to identify Semipalmated Plovers among flocks of Common Ringed Plovers.

Range, Records and Pattern of Vagrancy

Lets gloss over some brief compulsory range information.Semipalmated Plover breeds across the northern portions of the Canadian Arctic, and Alaska, south to Newfoundland and perhaps parts of Nova Scotia. The very similar Common-ringed Plover is primarily an Old World species breeding across northern Eurasia and making it as far south as Northern France.

In North America, Common ringed Plover breeds in Greenland as well as, Baffin Island and perhaps in scattered locations in Alaska as well. Semipalmated Plovers winter in parts of the southern US and throughout coastal South America. Common-ringed Plovers on the other hand head for extreme southern Europe and Africa.

Common ringed Plover also occurs as a vagrant species in North America. It is extremely rare outside of Alaska  and Baffin Island but there are at least accepted records for 6 US States and 4 Canadian Provinces (based on current eBird data). However, there are more records for Eastern Newfoundland, than for the rest of Canada (excluding Baffin Island) and the lower 48 combined, with near 20 records since 2006! Below are all of the records for Common Ringed Plover in eBird.

Records for Common Ringed Plover for Mainland Canada and the Lower 48

1989, Nova Scotia - October 7th (no details)
1990, Massachusetts - September 5 (adult)
2000, Quebec - July 7th (adult)
2003, New Brunswick - August 26th (adult)
2006, Washington - September 23rd (juvenile)
2010, Massachusetts - September 11th (juvenile)
2010, Quebec - May 29th (adult)
2011, California - August 24th (adult)
2013, Massachusetts - May 20th (adult)
2014, North Carolina - May 15th (adult)
2014, New York - August 24 (adult)
2016, Ontario - August 20th (adult)
2016, Illinois - September 14th (juvenile)
2017, Nova Scotia - September 1st (heard only)
2017, Massachusetts - September 12th (juvenile)

There are a total of 15 records for mainland Canada and the lower 48 (listed in eBird). There is some notable information which can be gleaned from these records. First, notice the increase of records from 2010 onward. I think there could be a number of factors at play, but chief among them are, more birders and a better network connecting them ; the boom in digital bird photography, which has allowed many of these birds to be photographed and the ID's confirmed ; better field guides and photos on the internet, which have improved our ability to id cryptic species such as Common Ringed Plover.

Of the 15 records, 12 are adults and just 3 are juveniles. This makes sense, since juvenile Common ringed Plover can be very difficult to identify in the field. I think it is likely that there will be an increase in the number of juveniles identified over time, as our ability to separate them from the extremely similar Semipalmated Plover improves.

It's also worth noting the timing of the records. The vast majority of the records are in late summer, primarily the last week of August through the first half of September. It would seem that adults are possibly any time during the late summer shorebird migration, while records of juveniles were confined to mid September. This is not surprising, since juveniles of most shorebird species migrate later than adults. I will discuss the Spring records separately, later.

Records for Common Ringed Plover for Newfoundland

1980 - August 24, (adult)
         - September 21 (adult)
2001- August 15th (adult)
2006- August 20th (adult)
          September 16th (adult)     ( an adult female and juv at the same location)
          September 16th (juvenile)
2007- September 2nd (adult)
2008- July 27th (adult)
2009- September 15th (juvenile)
2010- August 7th (adult)
2011- September 4th (juvenile)
2013- August 16th (adult)
2014- August 23rd (adult)
          August 15th  (adult)
2017- July 29th (adult)
          July 10th (adult)
          August 5th (adult)
          August 19th (adult)
          August 26th (adult)
          August 28th (adult)
          August 29th (adult)
          September 10th (adult)

Many of the Newfoundland records come in two years, 2006 and 2017, when there were 4 and an astounding 8, different individuals recorded. The CRPL invasion of 2017 (to eastern Newfoundland) probably merits its own article, and that is something I will explore at a later date. Other than the two big years, Common Ringed Plover is essentially annual in eastern Newfoundland, though it was notably absent from 2015 and 2016.

For a discussion of the 2006 influx, see the following North American Birds article " An Influx of Common Ringed Plovers in Southern Newfoundland in autumn 2006" I coauthored with fellow birder, Jared Clarke.

It is also worth noting that distribution of the records of CRPL in Newfoundland. All, but two of the records are from the eastern or southern edge of the Avalon Peninsula. This is probably partly due to the eastern facing edge of the Avalon being well positioned to collect stray birds from Europe, but it's also worth noting that this is by far the most birded part of the province. There are many excellent shorebird areas in other parts of the province, that get sparse coverage at best, so undoubtedly many CRPL's must pass through Newfoundland undetected.

The timing of records for CRPL in Newfoundland seem to mirror those of records elsewhere in North American, with adult occurring from mid August though early September and juveniles almost exclusively in the first half of September. As well, the proportion of adults to juveniles is also very similar, with 3 of 22 CRPL's in Newfoundland being juveniles and 3 of 15 CRPL records outside of Newfoundland pertaining to juveniles. As stated above I would expect to see the number of records of juveniles increase as our ability to identify them with confidence increases.

Where do Vagrant Common Ringed Plovers Originate?

There are 3 subspecies of Common Ringed Plovers (Charadrius hiatcula)

C.h.psammodroma- breeds from the Ferroe Islands and Iceland to Arctic Canada

C.h.hiatcula- breeds in Britain, south Scandanavia, Northern and Eastern Europe

C.h.tundrae- breeds from northern Scandanavia to Russia

It would seem to make sense that birds that have appeared Washington and California would belong to the Russian subspecies C.h. tundrae, since that is the commonly occurring species in Alaska. As for the records in the eastern half of North American, the situation is a bit more murky, with perhaps both psammodroma and hiatcula possible. Separation between these subspecies is difficult and to my knowledge people have not tried ( or have not been successful) identifying vagrant CRPL's in Eastern North America to subspecies.

C.h.psammodroma migrates from it's breeding grounds in Arctic Canada and Iceland to the coastal Africa. It is conceivable that these individuals get drifted off course, or perhaps some individuals get mixed up in flocks of Semipalmated Plovers. To me of more interest are the few Spring records of CRPL.

The vast majority records for vagrant Common Ringed Plovers in North America are in late summer, as part of the annual autumn shorebird migration. Only 3 off the 37 records documented in this article are Spring records, all occurring in late May. Interestingly, there aren't any Spring records for Newfoundland. This is notable since Newfoundland routinely gets European (Iceland bound) shorebirds in Spring, with European Golden Plover being annual and a number of records of other European shorebird species including, Common Redshank, Black-tailed Godwit, European Oystercatcher etc. I think the Spring Common Ringed Plovers on the eastern seaboard, are birds that had been drifted to  Eastern North America in fall and then over winted with Semipalmated Plovers in the extreme southern US or South America and then migrated back North along the east coast of North America, where they are then detected. This is the situation that is thought to be responsible for many Spring records of Ruff, Little Egret, Garganey and other European species.

Common Ringed Plover Identification (adults)

It is my experience that adult Common Ringed Plovers stand out fairly well in a group of Semipalmated Plovers, provided you have some experience with Semipalmated Plovers. Even from a distance they often appear slightly paler, perhaps slightly larger, with a distinct supercilium that trails the length of the auriculars. Common Ringed Plovers often appear as though the black face mask has been pulled more snugly, thus extending lower on the face. As well, often the entire auricular is black, extending all the way to the white band on the neck. In Semipalmated Plover the facials mask often fades to brown as it nears the side of the neck. All of this combines to give Common Ringed Plover a more contrasty look to the head in general. These features, although subtle, combine to create a different looking bird even from a distance, and gives the observer reason for further scrutiny.
Common Ringed Plover in Newfoundland
The Common Ringed Plover is the first bird on the left. Note how it appears different from the two Semipalmated Plovers. Don't be concerned with trying to pick out fine detail, just note the different impression you get from the bird; the more contrasty face and paler upper parts.
There isn't always this much difference in the thickness of the breast band. Note also the more extensive white forehead, with sharper contrast against the paler head. Also note the difference in the face. See how the black lores of the Common Ringed on the left are consistently thick versus the Semipalmated on the right, whose lores thin notably near the bill.
Note the paler look of the Common Ringed on the left. Common Ringed's often appear a paler, sandier brown than Semipalmated. Also, note the more contrasty look of the face, created by more extensively black auriculars and a more impressive supercilium. 

So far I have focused just on the impression a Common Ringed Plover gives when you see it among a flock of Semipalmated Plovers, but things are quite that easy. now it's time to break down some of those details we mentioned above (and a few others) and take a closer look. Recognizing a possible Common Ringed Plover is only part of the work, now it time to focus on clinching the ID!

I am going to focus on several key features that help to distinguish these species. It's worth noting that most of these features are variable and there is some overlap between the species. I will explain, when necessary, which features are the most reliable and most useful and which have the most overlap.

The key features I will focus on are;

- face mask ( auriculars and lores)
- white forehead
- orbital ring
- bill size
- breast band
- upper parts colour
- toe webbing ( or lack thereof)
- wing stripe (in flight)

Face Mask (do the lores meet the gape)

By face mask I am referring to the black area on the face that wraps around the cheeks on the side of the face, from the auriculars to the base of the bill. Of particular importance is the width of the black lores and if they extend to meet the gape.

Common Ringed Plover head pattern
Collage of Common Ringed Plover facial patterns
Note** - how the lower edge of the face mask extends to meet or dips just below the gape.
             - also note the shape and extent of the white supercilium. Note how it trails along the upper edge of the dark auriculars
             - dark orbital ring
             - note how the white forehead extends to form a point towards the inner edge of the eye, or even extending below the eye
Note how contrasty the faces of these Common Ringed Plovers above look with the extensive supercilium and dark face mask. Then compare these to the collage of Semipalmated's below. Pay particular attention to the gape, note the dark lores do not meet the gape line on the Semipalmated Plovers below. Also, notable are the pale orbital rings and much less extensive or lacking supercilium (this is quite variable). It's also worth noting the white fore head. Notice that Common Ringed Plover there is a greater tendency for the pale forehead area to reach the orbital ring or to terminate in the point just in front or below the eye. At this point you should be starting to see some notable differences in the head patterns of these two species. We will now compare the two side by side to highlight some of the features already discussed.

White Forehead Patch (shape and extensiveness)

One of the features that I've always found helpful is the shape of the white forehead in Common Ringed Plover and how it often forms a point reaching the front of the eye, or many times extending below the eye in a very narrow line. If you note above, Semipalmated seems ( I say seems because there is always an exception) to always have a relatively thick dark area between the white forehead and the eye. Below we will look at a couple of side by side comparisons to nail this important point home!

Comparison of Common Ringed and Semipalmated Plovers
Semipalmated Plovers above and Common Ringed Plovers below. Note the difference in the shape of the white forehead patch, especially how it forms a point towards the eye (and often reaches the orbital ring) in Ringed Plover. There is almost always some dark area separating the white forehead patch from the orbital ring in adult Semipalmated Plovers.
Orbital Ring Colour

The other important feature to note on the face of any Semipalmated or Ringed Plover is Orbital ring colour. Look again through the photos above and note the differences in orbital ring colour between the Common Ringed and Semipalmated Plovers. Any Common Ringed Plover being claimed in North America should have a dark orbital ring, just as any Semipalmated Plover being claimed in Europe or Asia should have some yellow or orange/yellow in it's orbital ring.

Having said that in high breeding plumage some Common Ringed Plovers DO have yellow orbital rings! This should be gone by the fall when most Ringed Plovers are seen in North American, but it might be a concern for potential Spring records.

Common Ringed Plover head, yellow orbital ring
Note the yellow orbital ring. Even if a bird such as this was seen in North America, it should be identifiable based on the extensive supercilium, and and facial mask which meets the gape. 
One character that people often cite when speaking of identifying Common Ringed Plover is the breast band and specifically how thick it is. While this is a not able feature, in my experience it is not at all reliable, there is some overlap between Common Ringed and Semipalmated Plovers in this feature AND the relative thickness of the breast band can change dramatically based on the birds posture.

Sure the breast band of an average Common Ringed is thicker than that of a Semipalmated, but it really is only a supporting feature at best. Note below some examples of breast bands in Common Ringed and Semipalmated Plovers.

Just to give an idea of how deceiving breast band thickness can be. The bottom bird is a Semipalmated Plover. This is probably the largest breast band I've ever seen on a Semipalmated Plover, but it shows the danger of relying too much on the thickness of the breast band for separating these two species.
Another feature that is of dubious usefulness is bill shape and size. I have seen 7 Common Ringed Plovers in Newfoundland. For most of those birds I could convince myself that the bill was larger; mainly longer, kind of appearing as though the outer 1/3 was extended just a little more. I think in direct comparison you can see that Semipalmated Plover does have a stouter, less tapering bill. However, this is very subtle and is likely some overlap involved, especially when comparing males Common Ringed's with female Semipalmated's or vice versa.

When it comes to separating Common Ringed and Semipalmated Plovers there are two absolutely fool proof characters to look for and they are, toe palmations and call. The problem is depending on how far away the bird is or the substrate it's feeding on, the feet may not even be visible and even if they are, you will probably want a photo to actually observe the webbing or lacktherof.

It is VERY important to note that both Common Ringed and Semipalmated Plovers have partial webbing (semipalmations) between the middle and outer toes (however, the webbing on Semipalmated is much more extensive). However, only Semipalmated Plover has webbing between the middle and inner toes. See the photos below to clarify this.

Comparison of toe webbing of Common Ringed and Semipalmated Plover
Semipalmated Plover left and Common Ringed Plovers on the right. Note the much more obvious webbing between the middle and outer toe of Semipalmated Plover and slight webbing between the middle and inner toes. Common Ringed on the right shows very slight webbing between middle and outer toes and no webbing between middle and inner toes.
Call Note

Aside from the toes other sure fool proof way to separate Common Ringed and Semipalmated Plovers is by call. Semipalmated has quite a sharp 'pew-it' or chu-wee, while Common Ringed has a much softer almost mournful 'too'li'.

The problem with using call notes for ID purposes is, it can be hard to isolate the call from one shorebird among a big flock, but if you can the call is certainly diagnostic.


That pretty much sums it up for the adults. In the Part ll of this article I will discuss the identification of juveniles and will also look at some more problematic individuals of both species. It's important to remember that when identifying either a Common Ringed Plover or Semipalmated Plover out of range, that a number of characters must be used to secure the ID, since there is overlap in some features and other features are very subtle.

In general most adult Common Ringed Plovers seen in North America, occur between mid August and mid September. They generally will appear paler than their Semipalmated congeners, with more contrasty faces, owing to a more extensive white supercilium, darker auriculars and dark lores that reach down to the gape. An important and apparently consistent feature is the shape of the white forehead, which is wider in Common Ringed and often reaches the orbital ring, terminating in a point at or below the eye. While Common Ringed Plovers have thicker breast bands on average than Semipalmated, this character should be used with caution, since there is much overlap and the apparent thickness of a birds breast band can change dramatically with the birds posture {whether alert with neck raised (thickest) or relaxed with neck squat down against the body (thinnest) }.When possible the two diagnostic features are the lack of palmations between the middle and inner toe on Common Ringed and differences in call note. While difficult to see in the field, quite often it's possible to obtain photos of the birds toes, which help greatly in securing the identification.

**Note** there differences in the amount of white in the wing, that I didn't discuss, mainly because I never had any good flight shots. I will discuss that feature in the follow up to this article and will update this article in time as well. As it stands there is more than enough information in this article to identify any out of range Common Ringed Plover.

Lastly, I would like to thank those who contributed photographs, namely my good friends and local Newfoundland birders, Bruce Mactavish and Alvan Buckley.

If you enjoyed this article you might also enjoy some of the other 120+ articles on the Birding Newfoundland Blog. Some of the latest articles include.

(select blog archive in pages, to see all previous articles)

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