ML645484234

观察细节

Watched this bird with Stefan Schlick as it flew up and down the Columbia River for approximately 25 minutes before we lost it. Large, mostly dark bird with white belly sharply demarcated and contrasting with dark breast and white underwing coverts. Typical Sulid shape in flight with long, pointed bill; long, pointed tail; and long, pointed wings. The bird was always too far away to easily observe characteristics necessary to conclusively rule out vagrant Brown Booby, though pattern of white on the underwing coverts, as seen through my spotting scope, appeared to be a better match for COBO than BRBO, as illustrated in the Sibley Bird Guide. Given that COBO is known to regularly stray northward along the Pacific Coast of North America and BRBO is not, the bird observed today was almost certainly a Cocos Booby and not a Brown Booby.