On 21 October 1984, we observed a Western Gull (Larus occidentalis) in third-winter plumage at the north shore of American Falls Reservoir, Idaho. The bird was subsequently seen there through at least 27 October.
First observed in flight among about 300 Ring-billed Gulls (Larus delawarensis), the bird was distinctly larger and had a darker mantle than any other gull present. From 15:30 to 16:30, we followed the bird as it moved from its initial location west to a boat mooring strip made of automobile tires. At this location, we were able to attract it by throwing bread toward it and the other gulls, enabling us to study the bird carefully at very close range.