Black-headed Gull vs Bonaparte's Gull

Black-headed Gull

Chroicocephalus ridibundus

Medium283 gCoastal

This gull is 34–39 cm (13+1⁄2–15+1⁄2 in) long with a 100–110 cm (39+1⁄2–43+1⁄2 in) wingspan and weighs 166–400 g (5+7⁄8–14+1⁄8 oz); males (186–400 g) average heavier than females (166–350 g), but with considerable overlap. In flight, the white leading edge of the outer wing (the outer primaries) is a good field mark, particularly combined with the dark underside of the inner primaries, which distinguishes it from the white underside of those feathers in its close relative the Bonaparte's gull.

ID text from Wikipedia, CC BY-SA 4.0

Recorded by Sonothèque ADVL · Aberrant, flight call · Vains, Manche, Normandy, France · CC0

Photo: Diliff · CC BY 2.5

Bonaparte's Gull

Chroicocephalus philadelphia

Medium203 gWetland

Bonaparte's gull is among the smallest of the gull species; only little gull and Saunders's gull are smaller. Adults range from 28 to 38 cm (11 to 15 in) in length, with a wingspan of 76–84 cm (30–33 in) and a weight of 180–225 g (6.3–7.9 oz). There is no difference in plumage or bare part colour between the sexes, though males tend to be heavier than females. Bonaparte's gull is smaller-bodied, smaller-headed, and smaller-billed than the other common hooded gulls of North America. Voice: Bonaparte's gull has a voice described as nasal and raspy, with calls variously transcribed as cherr or cheeer.

ID text from Wikipedia, CC BY-SA 4.0

Recorded by steve · Call · Petersburg, Petersburg Borough, Alaska, United States · CC BY-SA 4.0

Photo: David Menke · Public domain

Photos and recordings are credited to their authors under the licence shown. Full profiles: Black-headed Gull and Bonaparte's Gull.