Larus delawarensis
(Ring-billed Gull)

Physical Description:
17 1/2-21" (44-53 cm). Adults have white head, neck, underparts, and tail; wing tips black with large white spots; extensive blackish on underside of primaries; bill yellow with narrow black ring completely encircling the bill; feet yellow; reddish eye-ring. Immatures have pinkish bill with black tip; gray-brown above with whitish underparts; white tail with narrow black subterminal band; pinkish legs.

Similar Species- Mew, Herring, and California Gulls

Song:
A high pitched, shrill kyow kyow kyow.

Distribution:
Breeds from Washington east to Manitoba, and south to northeastern California, Colorado, and South Dakota. Also breeds in eastern U.S. and Canada. Nonbreeders occur in summer north to central Alaska, portions of western Canada, and south through wintering range. Winters coastally from southern British Columbia to southern Mexico (rarely south to Central America). Also winters on East Coast and in interior from Great Lakes to central Mexico.

Diet:
Feeds opportunistically on various animals, plant material, and garbage. Also eats insects and fruits.

Ecology:
Forages on land or water surface, or sometimes in vegetation; may take prey in air. Builds nest in matted vegetation on islands. Forms colonies. Pirates other nests. Fox predation may result in reproductive failure of local breeding colonies.

Reproduction:
Both sexes incubate usually 3 eggs (2.2-3.0 eggs in Idaho) for about 21 days. Young are tended by both parents, are fed until able to fly, and usually attain adult plumage in 3 yr. Adults may form female-female pairs or polygynous trios. In Idaho, colony size averages over 2000 nests.

Conservation:

Element Code:	ABNNM03100
Status:	Protected nongame species
Global Rank:	G5
State Rank:	S2
National Rank:	N5B,N5N

Important State References:
Trost, C.H. and A. Gerstell. 1994. Status and distribution of colonial nesting waterbirds in southern Idaho, 1993. Dept. Biol. Sciences, Idaho St. Univ., Pocatello. 74pp.