Last Sunday four of us went birding at Pymatuning State Park and found a single little gull flying among hundreds of Bonaparte’s gulls across the lake.
Little gulls are rare birds native to Eurasia who hang out in flocks of Bonaparte’s gulls in North America because the two are so similar. It takes a sharp eye to notice one.
Fortunately we were with Shawn Collins who has seen and photographed both species almost every winter in northwestern PA and northeastern Ohio. After Shawn pointed out the bird, it was easy to recognize. Shawn’s photos show us the difference between the two species.
Bonaparte’s gull (Chroicocephalus philadelphia):
“Bonnies” are very common small gulls in the Great Lakes region during fall and spring migration. They nest in trees in Canada’s boreal forest and spend the winter on the Atlantic and Gulf coasts and in the southeastern U.S. to Texas (map).
They’re best recognized by their moth-like flight style with bright white leading edges on their gray wings, seen from above and below. They have black tips on their primaries, also seen from above and below.
Notice the Bonaparte’s upperwings in the flock photo above and their underwings in two views below.
Little gulls (Hydrocoloeus minutus) are the smallest gull in the world but the size difference between little and Bonaparte’s is subtle. At this time of year the two have similar heads and backs in flight.
The real field mark for the little gull is its all-black underwings with white trailing edges. Once you see this, you also notice that the upperwing is all pale gray — not two-tone gray-white — and there are no black tips on their primaries.
Notice these features on the little gull at top and in the two photos below.
Now that you know the difference between them, here are two photos with both little and Bonaparte’s gulls. Can you tell who’s who?
And the hardest question of all: Is there a little gull in the flock photo above (second from top)?
(photos by Shawn Collins)