Sep 212017

Earlier this week I stopped by Whitesbog on the way to mom’s for lunch. I was a bit early, so I had an extra half hour or so before I was expected to arrive. What do you do with an extra half hour? Go birding, of course! The nearest local hotspot is Whitesbog, so off I went for what I thought would be a quick drive-through. As I pulled into the drained bog area, I found the water at nearly-perfect levels, with ample shallow water yet with exposed flats and grassy areas. The first bird that I looked at caught my attention, even while still driving. It was too white for most shorebirds, and was out in the water despite being small. I stopped the car, pulled out the bins, and found myself looking at a phalarope!

Phalarope and Yellowlegs

Phalaropes are very small shorebirds. Here it is in comparison to a nearby Greater Yellowlegs.

That was great, but now the question is which species of phalarope was it? Here in NJ, phalaropes fall into that category of birds that occur frequently enough to recognize them, but I do not see them frequently enough to feel comfortable identifying them without checking the field guides. In terms of abundance, Wilson’s Phalarope is the most common species here in NJ, followed by Red-necked, and with Red Phalarope being a review species that should be reported to the NJ Birds Records Committee. This bird clearly was not a Wilson’s Phalarope due to the dark eye patch, so the new default was Red-necked. But the bird was moving away, preventing high-quality photos or analysis. I tried to read this bird’s mind and anticipate where it was heading, drove to the cross-dike, and found that the bird reversed direction. Arghhh. While scoping it out, however, I spotted another nice bird, American Golden-plover. Oy! Is there such a thing as rare bird overload? The problem though, was I could hear the clock ticking and could sense mom wondering where I was and why I was late, while I was unable to get any great photos or know what this bird was. I had no choice but to get into the car and drive back to the original end of the bog and hope for better photos. I couldn’t re-find the Golden-plover, so full attention fell to the phalarope. The bird quickly took off, landing furthere away from where I was, but right next to the roadway. Here was my chance. I got out of the car, grabbed a few close shots, when it once again flew by and toward the water’s edge, finally allowing ample opportunity for documenting photos. I had to leave and hope that others would re-find it.

Phalarope bill2

The mostly white bird stood out among the mostly brown shorebirds present today.

Phalarope brown wings

Like most phalaropes, it was very active, feeding at twice the speed of any other bird in the area.

Phalarope eye patch

The bill looks quite sharp and thin from this view. But notice that little bit of rusty red color on its belly. That color shouldn’t be there in a Red-necked Phalarope according to the field guides.

When I arrived at mom’s I finally had an opportunity to look at the photos. Then I became confused. This bird had far too much red on it’s belly to be a textbook Red-necked Phalarope. Could it be a Red? Look at these photos and compare it to your field guide before reading further. What do you think?

Phalarope flight

The Phalarope in flight. This was the first photo where I noticed how much of a red belly this bird had.

Phalarope wings

Here’s a nice view of the upperwings in flight.

I texted a few friends in excitement, and after lunch went back to try to re-find the bird without any time constraints. Unfortunately it was nowhere to be found (by me or by others), so all we had were the photos. So what bird are we looking at here and what are the features that we should look for when we see a phalarope at this time of year?

Phalarope partially emerging

When the bird came into the shallow water edge, more of that rusty color could be seen.

Phalarope strolling

Here we can see even more of the red belly, and get a look at its legs.

The key features to note on this bird are the black eye patch, the rusty belly, and the relatively sharp bill. As we said earlier, the black eye patch eliminates Wilson’s Phalarope. The red belly points toward Red Phalarope, but the relatively pointed bill favors Red-necked. So where does that leave us? After studying this bird and the field guides there were two options. Either my judgment of bill shape is off and this is a Red Phalarope, or the bill shape assessment is correct, and this is a stained Red-necked Phalarope. If there is one theme that I have learned in bird identification, it is that structure trumps plumage. Bird structure (size, shape, leg size, wing length, bill shape) is amazingly consistent, while plumage changes; mutations cause pigmentation issues, food choice can affect feather color, molting or feather loss results in feathers at different plumage stages, and feathers can be affected by mud or oil or staining. As one example, think back to all those Snow Geese that you see with discolored plumage on their necks or undersides.

I showed the photos to people whose opinion I trust, and everybody agreed that the bill is not blunt enough for a Red Phalarope, and they uniformly agreed that it was a stained Red-necked Phalarope.

Does staining of birds happen frequently? I already cited the example of Snow Geese, but have heard of other tough identification cases involving stained shorebirds. A quick non-exhaustive on-line search revealed a passage from a book by Scott Weidensaul where he described birds that are stained by iron oxide in the arctic mud. That would be consistent with the breeding grounds of Red-necked Phalaropes in low Arctic bogs and marshes. Another book more specifically mentions Red-necked Phalaropes in the following passage, lending support to the origin of the red color in today’s interesting bird.

Screen Shot

 Posted by at 5:19 PM
Aug 312017

It was the kind of day where I just had to go out birding. The skies were clear, the temperature was ideal (in the mid-80’s), and the winds were light and coming from the west. There HAD to be something good out there, right? And even if there wasn’t, it was a perfect day to search for them, so Jeanine and I ventured out to the Sedge Islands again.

The Sedges have been good to us this year. Every trip there yields good numbers and quality of birds at close range, and there’s always the possibility of a rarity. For me, an average day at the Sedges beats a good day almost anywhere else nearby. Today my sights were set on either American Golden-plovers, which are popping up at the sod farms in nearby counties, or on one of the really unusual terns.

We arrived later than usual, with the tide already rising. Our first pass through the main flats didn’t yield anything remarkable, with the highlight being a large gathering of 70 Royal Terns. We couldn’t turn any of them into a Sandwich Tern, like we did last week.  At the inlet it was relatively quiet, although its always nice to see a flock of around 30 Brown Pelicans (‘normal’ for the Sedges), and a scraggly Red Fox patrolling the beach, trying to figure out how to convert one of the Common Terns into a meal. Returning back to the main flats, most of the birds now were concentrated into a relatively small area as it approached high tide. The goal of finding an American Golden-plover became more realistic upon seeing a sizeable flock of Black-bellied Plovers gathered on the edge of the water.

Plover pack

Here is a portion of the gaggle of Plovers that we found today. Can you spot the American Golden-plover in the crowd? It’s in there somewhere. We’ll come back to this photo later. Notice all the plumage stages on these plovers. Click on the photo for a larger version.

Jeanine and I spotted the bird at about the same time. I don’t always know what makes a tough bird stand out, but something stood out about this bird. The Cape May school of birding would just say that it was the GISS (or ‘jizz’) of the bird. Most of the time we prefer not to see an interesting bird walking away from us when we’re working on an ID, but in this case it was very helpful, since a definitive field mark is the black undertail of the American Golden-plover compared to the white undertail of the Black-bellied Plover. That sealed the case.

Butt shot

I’m not always hoping to see the underside of a bird, but in this case it was helpful to see those remaining black splotches on the undertail.

We tried to approach closer, but the bird had a comfort zone, and as soon as we approached 10 ft closer, it ambled 10 ft further away. It was a fun game that we repeated a few times (we sneak closer, it shimmies further; we try a different direction, it goes in a different direction, etc. etc.) , but ultimately we were happy with our views and switched to being distracted by the terns (more about them tomorrow).

American Golden-plover2

The field guide view of American Golden-plover. The combination of gold, brown, and white highlights on the feathers was delightful to view in person.

American Golden-plover feeding

American Golden-plover feeding. Here you can see the undertail molting from black to white. Black-bellied Plovers have an all-white undertail.

American Golden-plover flight

American Golden-plover in flight.

Before we leave for today, it is worthwhile to compare American Golden-plover (AMGP) and Black-bellied Plover (BBPL) in more detail; what can we look for when trying to find an AMGP in a group of BBPLs? The field guides mention several field marks. American Golden-plover is a tad smaller and has a slightly smaller bill than Black-bellied Plover, but the size difference is very tough to distinguish unless you are fortunate to have a direct side-by-side comparison, and apparent size changes depending upon posture. I would consider size a secondary trait, and not one that I would use to scan through a flock.  The bill size can be particularly important when the birds have completed their molt into non-breeding plumage, but again, it would be tough to use as the primary search criterion. As we mentioned earlier, the undertail color is important, but relies upon at least some remnant of breeding plumage. If the birds are in breeding plumage, this would be a good mark to search for, but it requires that they are facing sideways or away from the birder. For example, in the photo at the top of this post, all the birds are facing into the wind towards the camera, so the undertail is not visible. In flight, the underwing pattern is definitive, but that often relies up on a fleeting glimpse. All of these field marks help. Searching for golden tones to the feathers doesn’t work for me, since that seems very lighting-dependent and plumage dependent. For example, a flock of Black-bellied Plovers at this time of year can have some individuals that look nearly gray and other that have a tinge of brown.  I think that we can all agree that in the photo below, even the Black-bellied Plover looks somewhat golden.

Plover comparison

Here’s a pretty nice side-by-side comparison of an American Golden-plover on the leftt, with the more common Black-bellied Plover. Note the slightly smaller size, smaller bill, and speckled undertail of the American Golden-plover.

So what is the best field mark to start with? For me, the quickest way to scan through a mixed flock is to search for the bird with the prominent white supercilium that highlights a darker cap. Let’s re-examine the original photo that was at the top of this blog entry. Click on the photo below for a larger version, and then scan quickly looking for that bold supercilium and see if you can find the AMGP now.

Plover pack

Can you spot the American Golden-plover in this crowd? Click on the photo to get a larger version, and look for the prominent white supercilium.

OK, in the next photo the group has shifted slightly, and the bird is now more obvious, with the spotted undertail visible and the shorter bill. See, it’s not that hard after all, is it?

Plover pack3

OK, now that it turned sideways and I added an arrow, the American Golden-plover is more obvious. Click on the photo for a larger version.

This was the first American Golden-plover reported in the county this year, and there were only two reports in 2016. So it definitely qualifies as a nice find.

 Posted by at 10:16 PM
Jan 082017

A highlight of winter birding for me is looking for alcids. Sighting any member of this family of birds from land feels special because alcids spend most of their time in the open ocean. One drawback, however, is that sightings can often be less-than-optimal, either from a distance or of birds quickly flying past offshore. Because sightings can be fleeting, it is beneficial to know which alcids can be expected to appear in your area and to be prepared on how to distinguish them. I just completed my annual personal alcid refresher session, and thought it might be useful to share some general features of the alcids, and then focus on those that can been seen in my home turf of New Jersey.


A breeding colony of Common Murres. Don’t you wish that we could see this many in NJ?

The alcids are a relatively small family, with only 24 species world-wide, 21 of which occur in North America. They are strictly a northern family, not normally found south of the equator. Although most birders would probably guess that they are most closely related to penguins, they are actually more closely related to gulls. They have a completely marine lifestyle except for breeding on land. Interestingly, alcids have diverse breeding strategies, with puffins nesting in burrows, murres and Razorbills nesting on steep cliffs, Kittlitz’s Murrelets nesting on open tundra, and Marbled Murrelets nesting in trees. They are extremely proficient divers that rely on their wings for propulsion, like some ducks (Long-tailed Ducks, Eiders, and Harlequin Ducks), but unlike loons and grebes, which use their feet for propulsion. Their wings therefore are relatively short and stubby, well-designed for underwater ‘flight’, but ill-equipped for soaring. This adaption results in flights that are typically low to the water and consist of continuous wingbeats. Most alcids are counter-shaded, being mostly black on top and white below. Putting all of this together, any time I am near the shore in winter I look for smallish short-necked low-flying birds with black uppersides and white undersides that together should distinguish them from any grebes (which are not often seen in flight), loons (which are much larger), or ducks. Although these characteristics describe the family in general they don’t allow distinguishing the species. So once we spot an alcid, how do we begin to distinguish them from each other?

First of all, it is extremely useful to know that only seven alcids have been seen here in New Jersey, greatly simplifying the problem, and only five are very likely from land. A reasonable place to start is with relative abundance; which species are we most likely to find? Of the seven NJ alcids, Razorbill is by far the one most frequently observed from land, followed in frequency by Dovekie, Thick-billed Murre, Common Murre, and Black Guillemot. At the other end of the spectrum, Atlantic Puffins are rarely sighted from land, and Long-billed Murrelet has only been seen once in the state.

A second useful criterion is size. The three largest species (Thick-billed Murre 18″; Common Murre 17.5 “; Razorbill 17″) are in a similar size range as Red-necked Grebe (18″) or Black Scoter (19″), while the next two (Black Guillimot 13″; and Atlantic Puffin 12.5″) are in the same size range as Bufflehead (13.5″). At 10″, Long-billed Murrelet is noticeably smaller than Bufflehead, while Dovekie, at 8.25″ is tiny, being the same size as a European Starling. Imagine trying to find a Starling floating on windy seas! Being able to estimate the size relative to the more familiar loons, grebes, or ducks in the area is a great start to the identification process.

Beyond size, what other features can we look for to distinguish these species?  Most birders would rely on plumage, but with the exceptions noted below, plumage of most alcids doesn’t help me very much because most of them are black on top and white below with a white neck. So I like to focus on structure: the size, shape, and proportions of the bird. Let’s start with the most common candidate. Razorbill has a longer tail than the other alcids, extending the same length as the legs, resulting in a symmetrical, football-like appearance in flight, unlike the similarly-sized murres, where the legs extend beyond the tail. At close range, its broad bill with both horizontal and vertical white lines is distinctive.


Razorbill in breeding plumage. The blunt bill with its horizontal and vertical white lines is distinctive at close range.

Distinguishing between the murres is a challenge, since they have relatively similar plumage patterns. Thick-billed Murre is seen more frequently from shore than Common, has a blacker head, and tends to hold its bill level. It’s a heavier pot-bellied bird, so it has labored takeoffs from water. Common Murre is less common from shore than Thick-billed, has a browner head and back, and its bill tends to be held pointing upward. In winter, it has more white on the face than Thick-billed. That combination of whiter face and upturned bill makes it Red-throated Loon-like vs. Thick-billed with its level bill and darker face being Common Loon-like.


Thick-billed Murre with a Common Loon, showing the extreme size difference. Even though Thick-billed Murre is our largest eastern alcid, it is not even close to being loon-sized.


This photo of a Thick-billed Murre from Manasquan Inlet nicely shows how the longer legs protrude beyond the body. For a Razorbill, the legs extend only to the tip of the tail.


Common Murre has a noticeably browner head and back, although perhaps not always as evident as this specimen, which is from breeding season.

Dovekie is best distinguished by its tiny size and short blunt bill. They have proportionately long wings for an alcid, and because it is not very heavy, it takes off quickly from water. Its wingbeats are too fast to count or even to see. For these reasons, Pete Dunne cleverly refers to Dovekie as ‘The Bumblebee Alcid”.


The diminutive Dovekie. Notice the blunt bill and short perky tail.

Black Guillemot has the most distinctive plumage of the alcids, at least in winter when most of us get to see them. It is a pale bird, with a mostly white face and body, and large white wing patches all year. It can be seen most often on rocky coasts, where it prefers to forage. Its red legs are visible in flight.


Black Guillemot in winter. It is the only eastern alcid that is mostly white in winter. Photo by Dave Koehnlein.

Atlantic Puffin is the most recognizable alcid, at least with its oversized bright orange bill and orange legs that should be obvious in flight. It is the only eastern alcid with a black throat/collar year-round, unlike the other alcids, which have white throats in winter. Puffins like deep water of the continental shelf, so they are unlikely to be seen from shore, except perhaps after storms.


The Atlantic Puffin is unmistakable at close view. In flight, its orange bill and feet stand out. Notice its black neck, unique among our alcids in winter.

Keep an watchful eye out for this interesting group of birds. Because they are relatively uncommon, it can take some effort to find them. I have taken to sitting patiently on a folding stool at inlets in winter, scope at my side, especially on more tolerable warm and calm winter days, ideally after easterly winds have blown birds landward. Maybe I’ll see you there too.

 Posted by at 11:14 PM
Sep 282016

When I first started birding I had a tough time distinguishing the two largest terns in our area, Caspian Tern and Royal Tern. After all, they both have big red or red-orange bills and black caps, right? It has become much easier with time and experience, so if you have problems with these species, I’ll share a few photos and tips. But first, here’s a test: are these Royal Terns? Caspian Terns? Or a mix of both? If so, how may are Royals, and how many are Caspians? If you aren’t sure, then read on. The answer will be provided at the end of this post.


Royals, Caspians, or both?


It’s tougher when they are isolated. Royal or Caspian?

First of all, both of these terns are LARGE compared to the medium-sized Forster’s and Common Terns, and enormous compared to the tiny Black or Least Terns. The head-to-tail tern sizes according to Sibley are: Caspian 21″, Royal 20″, Sandwich 15″, Gull-billed 14″, Forster’s 13″ Common 12″, Black 9.75″, and Least 9″. So start with size to narrow down any terns that you see, especially if other terns are in the mix. Caspian averages just an inch larger than Royal, but it’s tough to distinguish them just by size unless they are side-by-side, and even then the difference between the two species is not always apparent.


The two largest tern species stick out in a group of other terns strictly by their size. Here’s two Royal Terns mixed in with and towering above Common, Forster’s and Black Terns.

A second clue can come from their abundance and breeding range. Caspian Terns breed in small numbers here in NJ; Royal Terns do not breed here, with the nearest breeding location being in the Chesapeake Bay region. In the east, Caspian Terns breed mostly in Canada and along the Great Lakes, and therefore can be seen inland in spring when they are migrating through, while Royal Terns are more southerly breeders that are nearly always near the coast. Both species start appearing here in larger numbers in late summer and early fall when they disperse from their breeding grounds or when the Caspians migrate back through. Royal Tern numbers increase first, and Caspians increase later. Although surprises can occur, it’s useful to have expectations, so look up the relative frequency and timing of these species appearing wherever you are birding.

Although expectations can help guide us, ultimately we need to get down to the key identification points. With these species, the most important characteristics are the bill and the cap. The field guides will tell us that the bill of a Royal is huge and orange-red while that of a Caspian Tern is huger and redder. And for younger birds the Royal has a yellow bill while a Caspian has a light orange bill. Really? Can we distinguish red vs orange-red and yellow vs light orange, especially when the lighting can change our perceptions? Surprisingly, the answer is yes, especially with experience or when there is a mixed flock. But another thing to look for, especially using a scope or if you get a close look, is the smudgy tip on the Caspian Tern bill. Look at the photos below for some examples.


Royal Tern in breeding plumage. Notice the orangey bill and the lack of a smudgy tip. The bill is also less bulky than that of Caspians.


Caspian Tern in near-breeding plumage. The color of the bill is on the red end of the red-orange spectrum, but by itself it’s still tough to judge confidently. The smudgy tip confirms the ID.

Perhaps the easiest distinguishing feature between these species is the cap. As you can see above, both species have all-black caps in breeding plumage, but the Caspian Tern retains that full cap much longer. Royals have the full cap from March to June, while Caspians have it from February to October. Any large terns with a ‘Friar Tuck haircut’ from June through mid-September will be Royals (although the smaller Sandwich Terns have the same look too…see below). The Caspians don’t lose as much of the black either, even late in the season, so they never reach full ‘Friar Tuck’ mode.


Four Royal Terns in late September, The complete black cap is now a ‘Friar Tuck haircut’. They have looked like this since June. Compare with the Caspian Tern photo below taken on the same day.


Three Caspian Terns in late September when they just start to lose their cap. Although there is variability in how much black remains in the cap, they never lose as much of the cap as Royal Terns. The smudgy tip is quite obvious in this close-up photo. Notice that the bill color is only slightly different from the Royal Terns in the previous photo. Look for the smudgy bill tip if you’re not sure.


An immature Royal Tern in July. Note the yellow bill, fleshy legs, black tips of the feathers on the back, and the lack of a full black cap. All are characteristics of young Royal Terns.


Look out for Sandwich Terns, which are also larger than our mid-sized terns, and also have a distinct ‘Friar Tuck haircut’. They are much more rare in NJ than Royals, and have a black bill with a yellow tip.


Here we have three Sandwich Terns next to a Royal Tern, to show the size comparison. Look for Sandwich Terns mixed in flocks of Royal Terns.

Good luck trying to find and distinguish these birds. As with all birding, it gets easier with practice. Regarding the quiz photo at the top of this page (taken in August), there are five mature Royal Terns (with the funky haircut and orange bill), two young Royal Terns (with funky haircut and yellow bill), and a single Caspian Tern (with full dark cap and deep red bill) sitting down near the center of the photo. The second photo shows a single adult Royal Tern.

 Posted by at 6:22 PM
Aug 112015

Yes, its a tern, but which one?  Can you identify it with confidence?  If not, then read on.

OK, you’re out birding and you see the excellent individual shown above. Many birders will be able to recognize this bird as one of the medium-sized terns, which here in the eastern US narrows down to Forster’s or Common Tern. But which is it? For far too many birders, this is a tough call. Like many birders, I struggled with these terns for a long, long time. For FAR too long, I felt like I was just guessing when I saw a medium-sized tern, hoping that the habitat would push the odds in my favor (Forster’s Terns prefer marshes, while Common Terns prefer beaches). That was frustrating to me because bird identification should be based on observation of specific features and shouldn’t feel like a coin toss. Well, this year I decided to do something about it and worked at trying develop confidence in identifying these species correctly. (Actually, although I say that I worked at it, that’s not completely true, since this minor quest became an utter pleasure and was the furthest thing from work.) Today I will share some of my thoughts on distinguishing these two species in the hope that my experience might help some of you.

OK, to start us off, what do the field guides tell us to look for on these terns? Well, Forster’s Tern is supposed to have a light orange bill, whiter body and wings, a tail that extends beyond the folded wingtips, and longer legs, while Common Tern sports a deeper orange bill, gray body and darker wings, a tail extending the same length as the wingtips, and with black on its outermost tail feathers. Although all of those points are indeed true, for me they were either difficult to distinguish in the field (Is that bill light orange or deep orange? Is that body gray or does it just look gray because it is shaded from the sun?), or they were difficult to see (the edging on the tail feathers is seldom apparent even in good lighting, and only in flight). Far too often my decision changed depending on the lighting conditions; a bird would look like it had a gray body in flight, having me lean toward Common, and then it banked toward the sun and miraculously it was transformed into a white-bodied Forster’s. Drat. The same thing happened when trying to decide how orange the bill was; a well-lit bill could look light orange (perfect for a textbook Forster’s), and then when the head turned and the bill became shaded, it was suddenly the deep orange bill of a Common Tern. Ugh. I was ready to wave the white flag and surrender.

Now after observing several hundreds of these birds this summer, often in locations where both species are found intermixed, I feel like I’ve finally broken through. Part of the reason is purely the additional experience, and partly its because now I’ve found identification points that work for me. When the birds are resting on a beach or mudflat, I now focus on two features: the color of the folded wingtips and the bill color. For me the folded wingtips are actually more reliable, with the Common Tern having black wingtips and the Forster’s Tern having grayish wingtips. Look at the terns in the photos below and decide purely on the wingtips and you should come to the correct conclusion.

Common tern side view

If we start with the bill color, I would have a hard time deciding if this is a Forster’s or Common Tern, perhaps leaning slightly and uncomfortably towards the darker bill of a Common Tern. But look at the wingtips…they are jet black, unmistakably characteristic of Common Tern.

Forster's Side view

Which tern is it? Start with the folded wingtips. In this bird the wingtips are gray, pointing towards Forster’s. The lighter orange bill compared to the previous photo of the Common Tern confirms the conclusion.

Of course, it helps that in these photos the birds are in nearly perfect lighting and in the textbook profile pose, but we have to start somewhere. For me the bill color is somewhat debatable, but the wingtips aren’t, and using the combination of both leads to a much more reliable conclusion.  To put further icing on the cake, when both species are present together, the comparisons are easier and allow us to introduce one more feature: leg length. Look at the two terns in the photo below and decide what you think they are. Then look at the leg length. Does one of the birds have longer legs than the other?

Common and Forster's Terns2

Decide which species you think these are, note the leg length on these birds, and read on.

When they are side-by-side like this, things get easier; the bird on the left has a deep orange bill and black wingtips (= Common Tern), and the one on the right has a lighter orange bill and gray wingtips (= Forster’s Tern). But note the leg length; the Common Tern has shorter legs than the Forster’s, just like the field guides say. Leg length is hard to judge when they are not closely juxtaposed like this, but can be another supporting feature to look for in mixed flocks.

So that’s what I focus on with resting birds. How about when they are in flight? At times this can also be surprisingly easy. I used to look at the undersides of the bird…the body and wings, whereas now I focus on the upper surface of the wings. For me, looking at the lower wing surface or body was frustrating because it was so dependent upon lighting, and with the sun being above, these areas alternated between sun and shade during flight, turning identification into a guessing game. The upperwings are more often well-lit, thereby allowing for more reliable views. Common Terns have upper wing surfaces that are almost uniformly gray, with a fairly large patch of black at the wing tips. The upper wings of Forster’s Terns, on the other hand, are two-toned or three-toned, with the distal half of the wing (furthest from the body) being distinctly whiter than the half that is closest to the body, which is gray. There is also a smaller patch of black on the upper wing tips. So instead of trying to determine if the wings are light gray or dark grey (are they kidding?), try to determine if the gray is uniform or two-toned. With practice, you will find that you often can distinguish these two species at a surprising distance by focusing on the upper wing surface. Give it a try. Compare the photos of soaring birds below.

Common in flight

Classic view of a Common Tern in flight. Note that the upper wing is uniformly gray both before and after the ‘elbow’. There is also a fairly extensive black patch at the wing tips.

Forster's tern4

Forster’s Tern in flight. Note the relative lack of any black at the tip of the upper wings. The distal half of the wings beyond the ‘elbow’ are typically whiter than the proximal half, but its not so obvious in this slightly overexposed view.

One of the interesting things about Common and Forster’s Terns is that (unlike many other species) they are actually easier to identify when they are juveniles or are in non-breeding plumage. Forster’s Terns have a dark patch that is limited to the area immediately surrounding the eye, making them look like they just lost a boxing match, while Common Terns have a black patch that extends from the rear of the eye to the hind neck. Conveniently, in juveniles and in non-breeding plumage, Common Terns also contain a black ‘carpal bar’ on their wings that Forster’s Terns lack.

Forster's tern fall

Forster’s Tern in fall. The restriction of the dark patch to the eye and the lack of a carpal patch both point to Forster’s.

Common tern fall2

Common Tern in fall. Note the black patch on the hindneck, not surrounding the eye, and the presence of the diagnostic carpal bar on the wing.

Both species will have juvenile plumage that has additional touches of brown or ginger when they are extremely young in early summer, but the diagnostic black facial patches are present throughout their first year. The brown or ginger portions of the wing and body plumage wear away by late summer, leaving the mostly silvery late fall plumage shown above.

Juv Forsters Tern

Here’s a juvenile Forster’s Tern. The black eyepatch indicates that its a Forster’s. The ginger color on its body and wings is on the edge of its feathers. Those ginger tips will eventually wear off, leaving the silvery pattern that we saw above. Photo kindly provided by Karmela Moneta.

Common Tern immature

Here is an immature Common Tern in late July for comparison. Note the different pattern in the face compared with the immature Forster’s Tern. The dark ‘carpal patch’ is somewhat visible underneath some feathers. Later in the season this patch becomes much more visible as the overlying feather tips wear away.

During the mid-to-late summer, the presence of these juvenile birds greatly helps to identify the adults. If you find yourself by a large tern flock, watch for begging youngsters, which should be readily identifiable based on the black eye or neck patches, and see if you can identify the parents when they arrive to feed the young. Then watch the parents when they leave to see if you could identify them in flight. I found this kind of conformation and reinforcement to be extremely valuable.

There are a few other identification points that can be helpful, but their use is more limited than the ones discussed above. Forster’s Terns molt a little earlier in the season than Common Tern, so birds that are losing their black cap in July are likely to be Forster’s, whereas those retaining their full black caps in late August are more likely to be Common. This can vary between individuals, but can be fun to follow. Finally, the folded wingtips of Forster’s Terns can extend considerably further than the tail, but this is most easily seen early in the year. Those wingtips will wear away and become shorter as the season progresses and then becomes an unreliable indicator.

Common Tern outer retrices

A final identification point that can be helpful. The outer tail feathers of Common Tern are partially black whereas in Forster’s they are all white. This is usually difficult to see but is fun to look for.

Good luck using these identification points. Now its time to start working on shorebirds!


ps…in case you haven’t figured it out, the bird in the uppermost photo at the beginning of this post is a Common Tern.

 Posted by at 10:21 PM
Jan 252015

Gulls typically are not the favorites of most birders; they certainly don’t seem to have the same widespread allure that owls or raptors or warblers have. If you meet anybody who truly enjoys sorting through gull flocks, then you know you are in the presence of a hard-core birder. So why is it that gulls often achieve least-favored status? For most birders, I suppose that it revolves around three issues. First, gulls present identification challenges, as they can take two or three years to achieve maturity, with different plumage patterns for each year. Second, finding the more interesting or desirable gulls has a bit of a needle-in-a-haystack feel, requiring sorting through a large flock to find something different. Third, at least where I live, the more interesting or desirable gulls arrive in winter and I’m not a fan of sorting through large distant flocks through a scope while shivering. Especially at places like landfills (=garbage dumps) where gulls tend to accumulate.  Logically, I realize that the first two reasons are not very justifiable, as identification challenges and finding rarities are two aspects of advanced birding that make it such an enjoyable hobby, but hey, I’m not alone in these biases. During these past few weeks, however, I’ve found that studying gulls in Florida is quite enjoyable because cold weather is not an issue, and the gulls allow close approach on lovely beaches where even binocs often are not needed.

So today I thought that I’d share two of the interesting gulls that I’ve found over the past few days. A Franklin’s Gull has been making appearances at a local town beach located only five miles or so from where we are staying. As I’ve only seen Franklin’s Gulls once before, in Colorado, I thought that an early morning stop was worthwhile. When we arrived at the beach I was disappointed, since only two dozen or so gulls were present, and I expected much more. What were the odds that a Franklin’s would be in such a small flock? Well it turns out that we beat the odds, and here’s where the expertise of others came in handy. Franklin’s Gulls are difficult to distinguish from the much-more-common Laughing Gulls, with Franklin’s having a narrower bill and a more prominent white eye-ring. In the absence of knowing that a Franklin’s was appearing sporadically at this beach, I probably would have assumed that all of the darker-winged gulls were Laughing, and missed this rarity. (there’s a lesson embedded in here for us all!) But after sorting through the small flock carefully, a narrow-billed gull became apparent, especially in comparison with the accompanying Laughing Gulls. The dim early morning light allowed a diagnostic photo. To give an idea of its abundance, only two other Franklin’s Gulls have been reported on the east coast in eBird this year to date. My thanks go out to the fine birders who originally identified and reported this bird.

Franklin's Gull winter

A Franklin’s Gull in winter plumage in early morning light. The narrower bill and more prominent white eye-ring are key identification points for distinguishing it from the similar Laughing Gull.

Two days later I was scanning through the gulls and terns at our local beach that I have been trying to visit daily. Every day the combination of shorebird, gull, and tern species present here is slightly different, and I have been hoping for a Sandwich Tern to make an appearance. After a quick scan and finding the usual suspects, I noticed an immature gull that was intermediate in size between the accompanying Laughing Gulls and Herring Gulls. There aren’t too many possibilities within that size range, and after consultation with my well-worn Sibley’s Guide, it became apparent that I was watching a first year Lesser Black-backed Gull. Although its not nearly as rare as Franklin’s Gull, this bird also was flagged as rare at this location in eBird. Maybe gulling can be fun after all. At least when the weather is this warm and the birds are this accommodating.

Lesser Black-backed Gull

A first winter Lesser Black-backed Gull.

 Posted by at 8:42 PM