01 December 2022

November 2022 Quiz


February. Indiana.

Age: A large gull with black upperparts immediately narrows down our options to a four-cycle species. Given the adult-like white tips to the flight feathers, with brown markings on the underwing coverts and marked tail, we can be sure this isn't an adult, and best fits a 3rd cycle type.

Identification: Black-backed adults in North America can be approached by leg color, size/structure and wingtip pattern. The massive bill and head, all white tip to p10 (left wing) and pinkish legs point directly to Great Black-backed. Lesser Black-backed is ruled out by overall structure and wingtip pattern (note, some Lessers can show fleshy legs at this age). Western (and Yellow-footed) is ruled out by the white tip to p10. Slaty-backed Gull doesn't typically show this massive bill with large blocky head, and should have broader white tips to the trailing edge. Our November Quiz bird is indeed a 3rd cycle type Great Black-backed.