(starting from upper left and moving left to right)

1: Black-headed Gull (adult nonbreeding)

These guys are a European species and are becoming newly regular on the East Coast in wintertime! This particular bird is hanging out (with two of his friends) at a wastewater treatment plant in Delaware which is, thankfully for me, open to the public!

The main identification hurdle with Black-headed Gulls is that they look a lot like Bonaparte’s Gulls (8) and tend to associate with them when roosting or feeding, making differentiation difficult at times. The easiest way to know for sure is to look at the bill color - Black-headed Gulls have blood red bills while Bonaparte’s Gulls have thinner black bills. Black-headed Gulls are also slightly larger than Bonaparte’s Gulls and have more extensive black coloration on their underwings.

If you’re curious, the name ‘Black-headed Gull’ comes from their breeding plumage in which they (and Bonies as well) have fully black heads rather than just the spot they have in winter. The rest of their plumage remains largely unchanged from winter to summer. 

2: Great Black-backed Gull (adult nonbreeding)

This is the largest gull species in the world! You can tell this one is extra fierce because he is defending a cache of cheesy pretzels that someone dropped on the beach.

There’s very little that one might confuse with these certified Big Boys except for Lesser Black-backed Gulls (6) which essentially look identical to them in all cycles and plumages. As their name would suggest, however, Lesser Black-backs are smaller and, in adult plumage, are easily told from their larger counterparts by their bright yellow legs - Great Black-backs have pink legs their entire lives. 

I’ve also been told that a way to differentiate adult-plumaged birds is that Great Black-backs have slightly darker black mantles/backs than Lessers and... *throws hands up in the air* I GUESS!

3: Iceland Gull (2nd winter)

These guys are pretty easy since they are one of only two gulls on the East Coast to be known as the “white-winged gulls,” meaning that they have white primaries/wingtips regardless of age rather than black ones like every other species.

The other species of “white-winged gull” is the Glaucous Gull (which I helpfully do not have a photo of) and the main way to tell them apart is that Glaucs are really chunky while Icelands are less-so. That’s literally it. 

Icelands also tend to be less pale than Glaucs but this particular bird I photographed on my pelagic was quite pale so that’s not always a great field mark in practice. Just focus on the chonk. 

When they reach adulthood, both Iceland and Glaucous Gulls settle into the typical “white body, light gray mantle” plumage and superficially look a lot like Herring Gulls except for the color of the primaries which are still white.

4: adult nonbreeding Black-legged Kittiwake (center), 3rd winter Herring Gull (upper right), and 1st winter Lesser Black-backed Gull (bottom right)

okay one at a time here!

Kittiwake: 

I’ll hold off on going in-depth on this guy since I have two solo photos of him later in this set but they’re very cute! Look at him!

Herring Gull:

Like I said above, this guy is in 3rd winter plumage. This means that he is unusually ugly. Herring Gulls are just sort of ugly all the time regardless of plumage and they look very different from year to year until they reach adulthood. Oftentimes, I’ve seen people staring at a gull flock saying “I don’t know how to tell these apart!” when they’re really just looking at a group of differently-aged Herring Gulls.

Personally, I just consider them the generic “medium-sized gull” (since they’re the most common at the shore) and judge everything off of them. I don’t really have a lot of good ID tips for them... They look a little like Ring-billed Gulls (5) in adult plumage but they’re larger, have pale pink legs rather than yellow, and lack the prominent black bill ring that Ring-bills are named for (although they may have black or red splotches on their bills so don’t let that trip you up).

Lesser Black-backed Gull:

As I mentioned earlier, Great and Lesser Black-backed Gulls are almost impossible to tell apart, particularly in 1st winter plumage but the way I’m ID’ing this guy is by the thickness of the brown streaks on his chest and the way his head looks smaller than I would expect a Great Black-back’s head to look.

It’s a tough call though honestly, and I’d welcome a second opinion on this one.

5: Ring-billed Gull (adult nonbreeding)

The typical “parking lot gull” of the Mid-Atlantic! Sometimes spots near the beach get Laughing Gulls in the summer as well but, where I live, it’s all Ring-bills, babey! Who needs the ocean when you have concrete, amirite?

These guys are pretty distinctive. Relatively small with bright yellow legs and bill, and of course the black ring around the bill. As I said, they’re smaller than Herring Gulls (4) and they’re bigger than Laughing Gulls, Black-headed Gulls (1), and Bonaparte’s Gulls (8) - the latter two of which they associate with at that same wastewater treatment plant although I took this particular photo at the inlet!

6: Lesser Black-backed Gull (2nd winter)

I already discussed these guys vs Great Black-backs so I’ll try not to repeat myself too much!

Mostly including this one to point out that the 2nd winter plumage is much more patchy than 1st winter, with extensive white on the front and also because this photo shows the small head really well.

(Also, peep the Ring-billed Gull partially in frame there lol)

Fun fact: Lesser Black-backed Gulls used to only show up as vagrants from Europe but are now common here, particularly in winter. Maybe this is what the future looks like for Black-headed Gulls as well?

7: Black-legged Kittiwake (adult nonbreeding)

If you’ve never been far offshore, there’s a good chance you’ve never seen one of these cuties before (unless you live in Europe where they’re just all over the place for some reason. Y’all get Northern Fulmars from land too - what is wrong with your seabirds??) but they’re SO COOL! I’ve been lucky enough to see them breeding on sea cliffs on St. Paul Island, Alaska but seeing them at sea is unparalleled! The way they fly is so unique among gulls and has to be seen to be believed!

Identification-wise, they really don’t look like anything else in the Mid-Atlantic. One distinctive field mark is that their wingtips sort of look like they’ve been dipped in ink, forming almost perfect black triangles at the primaries. They’re also exceptionally small in comparison to Herring Gulls (4) and either species of Black-backed Gull (4), however, they’re only slightly smaller than Ring-billed Gulls (5) overall (but are pointier than Ring-bills if you compared them in flight).

If you go to St. Paul Island and have to tell them apart from Red-legged Kittiwakes, a good tip (other than the leg color, obviously) is that their mantles/backs are paler than those of Red-legged Kittiwakes and they’re slightly bigger.

8: Bonaparte’s Gull (adult nonbreeding)

This is an incredibly cropped photo but I didn’t want to leave the Bonies out! They’re just too cute!

They’re the smallest gull that normally occurs here (rarely we get vagrant Little Gulls which are REALLY small and make me cry because of their smallness) and, as I already compared them to Black-headed Gulls (1) in detail, I won’t do so again. The black line trailing along the edge of their primaries is pretty unique to them and, as I said before, their thin black bills are distinctive. The redness of their legs also tends to be more orangey-pink than that of Black-headed Gulls (1) but the legs look pretty dark in this particular photo so this is a good example of the fact that you should often throw individual field marks out the window and just view the bird as whole, comparing its look to those around it. 

As a small tangent based on that idea: oftentimes I’ll start to convince myself that one of the gross-looking Herring Gulls in those mixed-cycle flocks I mentioned earlier is actually something different and rare but then I stop and ask myself “is there anything about this bird’s build and structure that looks different from the Herring Gulls around it?” and, if the answer is no, then it’s just a Herring Gull that I was overthinking. Never a bad thing to step back, especially when looking at a type of bird as confusing as gulls can be!

9: Black-legged Kittiwake (adult nonbreeding)