Portland’s Westmoreland Park is a great place to find a variety of gull species during winter. Seven species and one hybrid are regular, and there is always the possibility of something more unusual showing up.
California Gull: medium-gray mantle, long dark wingtips that extend well beyond the tail, long straight bill with both red and black gonydeal spots, yellowish legs and feet with blue-gray cast.
Ring-billed Gull: smaller size, neat black ring around bill, long dark wingtips, yellow legs and feet.
Here’s the Ring-billed Gull at rest. Note the fine streaking on the head and the red orbital ring.
Mew Gull: petite yellow bill, round head, long wing extension. These small gulls will mix with the Ring-billed flock, but generally don’t mix with the larger gulls.
Glaucous-winged Gull: Note the lack of contrast on this bird. The short wingtips are the same color as the mantle. The head and upper breast are covered with an even blurry mottling. The only parts that don’t blend in are the pink legs and feet.
Western Gull: large size, dark gray mantle, short black wingtips, never any marks on the head – even in winter. This species is much more common on the coast, but a few make it in to the Willamette Valley in winter.
Western Gull X Glaucous-winged Gull hybrid (Olympic Gull): an even blending of characteristics of both parent species. The mantle is darker than a pure GW, but Westerns never show this much mottling on the head and neck. The wingtips are dark, but not actually black. You can tell this is a third cycle individual by the tiny bit of black on the tail and by the odd pattern on the bill. These hybrids show a great deal of variation, and are often the most numerous gulls in the area.
Herring Gull: sloping forehead, pale eye, bill not too thick, black wingtips that extend beyond the tail.
Thayer’s Gull: rounded forehead, thin bill, dark eye (usually, not always), long black wingtips with much more white on the underside.
The first thing you notice about this bird is the lack of contrast. The pattern is soft and blurry, and the primaries and tertials are the same color as the rest of the bird. The big head and substantial bill are also good for this species.
The pattern on this bird is very crisp, almost checkered. The tertials and primaries are darker than the rest of the bird. The primaries are two-toned; a dark leading edge and a pale trailing edge. This is the classic mark for Thayer’s Gull. The round head and thin bill are also important marks.
This bird’s pattern is fairly dark, but not as crisp as the Thayer’s. The tertials and primaries are blackish, and mostly solid. Note the sloping forehead and two-toned bill (heavier than Thayer’s but still fairly thin).
Ethical Birder 