Ring-billed Gull photo
Ring-billed Gull
Larus delawarensis
(Laridae)
Global Rank:
G5
State Rank:
S5B
Agency Status
USFWS:
USFS:
none
BLM:
none
General Description
Medium-sized, white-headed gull. Males: 46-54 cm, 400-700 g; females: 43-50 cm, 300-600 g. Pattern of plumage similar to Common Gull but upper wings and mantle distinctly paler contrasting noticeably with the extensive black on upper and lower surfaces of 5th and 7th primaries. (Ryder, John P. The Birds of North America, No. 33, 1993).
Economic Value
Ring-billed Gulls are becoming a potentially serious agricultural and urban-suburban nuisance species. They sometimes present a hazard to aircraft near airports.
Migration
In the Bozeman area, normal migration periods are April 2 to May 15 and August 25 to November 15, with peaks April 15 and Ocobert 1. Two adults banded at Freezeout Lake were later reported from Blackfoot, Idaho and Sonora, Mexico (Rothweiler 1960).
Habitat
Spring and fall migration prefers fresh water (lakes, river marshes, reservoirs, irigation and agricultural areas). Occurs inland more often than other species of gulls - near landfill sites, golf courses, farm fields. Winter range mostly on or near coast. Common around docks, wharves, harbors; scarce in pelagic waters; inland on reservoirs, lakes, ponds and streams, landfill sites, and shopping malls in large metropolitan centers. (Ryder 1993).
Food Habits
Main foods include fish, insects, earthworms, rodents, and grain. (Ryder 1993). At Freezeout Lake, stomach contents included insects, oligochaetes, crustaceans, birds and mammals, and plant material believed to be consumed incidentally to consuming animals (Rothweiler 1960).
Ecology
At Freezeout Lake, there was little interaction with L. californicus in mixed colonies. Species foraged at different distances from the colony, and nesting habitat was segregated with respect to vegetation into monospecific groups.
Reproductive Characteristics
At Freezeout Lake, first eggs were layed on May 1; by May 8 nests had 1 to 4 (mostly 3) eggs. Nests were constructed of dried bulrush; in many cases nests were less than 6 inches apart (Rothweiler 1960). Statewide, nesting begins in late April, with bandable young present in mid-June (Davis 1961).
Citations & Sources
- Lenard, S., J. Carlson, J. Ellis, C. Jones, and C. Tilly. 2003. P. D. Skaar's Montana Bird Distribution, 6th Edition. Montana Audubon, Helena, Montana. vi + 144 pp.
- NatureServe Explorer: An online encyclopedia of life [web application]. 2002. Version 1.6 . Arlington, Virginia, USA: NatureServe. Available: http://www.natureserve.org/explorer. (Accessed: March 20, 2003 ).
