Columbia subject headings:
Harvard subject headings:
Gulls--Behavior
Gulls--Ecology.
Gulls--Food.
Laridae--Behavior.
Plovers--Behavior
Plovers--Ecology.
Plovers--Food.
Shore birds--Behavior
Shore birds--Ecology.
Shore birds--Food
Princeton subject headings:
Birds--Behavior.
Birds--Ecology.
Birds--Food.
Gulls--Behavior.
Gulls--Ecology.
Gulls--Food.
Plovers--Behavior.
Plovers--Ecology.
Plovers--Food.