Birds generally seen on the wing, as a rule, over water. Bill strong, thick; hooked in the Gulls and Jaegers; sharply pointed in the Terns; often colored in part yellow or red; wings very long, the outer feathers much the longest; tail usually short and square in the Gulls, long and forked in the Terns; toes webbed. Color usually pearly gray above, white below in adult Gull and Terns; Jaegers and many young Gulls are dark.
Family 4. SKUAS AND JAEGERS. Stercorariidæ.
Toes four; three front ones webbed; bill with swollen, hooked tip, its base with a scaly shield.
Family 5. GULLS AND TERNS. Laridæ.
Toes usually four, three front ones webbed; upper mandible curved and hooked; tail usually square (Gulls, subfamily Larinæ). Bill straight and pointed; tail often forked (Terns, subfamily Sterninæ).
