The Pomarine Jaeger is the largest of the jaegers. Adults have long central tail feathers that are twisted 90 degrees, but these are usually lost after the breeding season, in mid- to late summer. Pomarine, Greek for ‘lid-nosed’, refers to the sheath that covers the base of the bill. The large, bi-colored bill contrasts with the dark face. Adults and juveniles have light and dark morphs, but 90% of the adults are light. The light morph has a blackish cap and dark brown upperparts, white underparts and collar, a yellow wash on the sides of neck, and a bold brown band across the breast. The dark morph is similar except the underparts, sides of the neck, and collar are entirely dark brown. Juveniles are brown with uniform head and neck and strongly barred coverts on the tail and underwing.