Gull ID is one of the fun yet frustrating and challenging aspects of birding. The great thing about gulls is that they are big, common, and they often sit around and let you study them carefully. The tough thing is that they are all shades of gray, white and black and to the untrained eye all look similar. I came across an excellent article by Dennis Paulson, one of our Washilngton superstars and noted bird identification author posted on the Puget Sound University website and recommend it as an aid to gull ID in the Pacific Northwest. To make it more useful I’ve added links below to use paragraph by paragraph as you read through the article, as for me pictures help me understand written descriptions:
Identification of Pacific Northwest Gulls by Dennis Paulson.
Flight Characteristics:
Flying Herring Gull vs. Flying Ring-billed Gull for look at wider relatively shorter wings of larger vs smaller white-headed gulls
Mantle Color: For quick reference here is a Kodak Gray Scale table for the mantle color of gulls, and a link to the colors on the scale.
0 Ivory Gull
3-4 Glaucous Gull
3-4 Ivory Gull
3.4-4.5 Ross’s Gull
3.5-4.5 Brown-headed Gull
3.5-4.5 Andean Gull
4-5 Glaucous Gull
4-5 Kumlien’s Gull
4-5 Black-headed Gull
4-5 Ringed-bill Gull
4-5 American Herring Gull
4-5 European Herring Gull
4.5-5.5 Little Gull
5-6 Boneparte’s Gull
5-6 Gray-headed Gull
5-6 California Gull (N Interior North America)
5-6 Thayer’s Gull
5-6 Glaucous-winged Gull
5-6.5 Common Gull
5.5-7 European Herring Gull
6-7 Yellow-legged Gull
6-7.5 California Gull (ours)
6-7.5 Mew Gull (N. America)
6-8 Glaucous-winged x Western Hybrid (Olympic Gull)
6.5-8 Kamchatka Gull
6.5-7.5 Black-legged Kittiwake
7 European Herring Gull x Lesser Black-backed Gull (Britain)
7-8 Black-legged Kittiwake (N Pacific)
7-8 Swallow-tailed Gull
7-8 Vega Gull
7-8.5 Yellow-legged Gull
7-9 Sabine’s Gull
8-9 Laughing Gull
8-9 Franklin’s Gull
8-9.5 Western Gull (N W USA)
8-9.5 Black-tailed Gull
8-9.5 Red-legged Kittiwake
8.5-9.5 Gray Gull
9-10.5 Yellow-footed Gull
9-11 Lesser Black-backed Gull
9.5-10.5 Lava Gull
9.5-11 Western Gull (SW USA)
9.5-11 Slaty-backed Gull
10-11.5 Heermann’s Gull
11-13 Lesser Black-backed Gull (N. Europe)
12.5-13.5 Dolphin Gull
12.5-14 Kelp Gull
13-15 Great black-backed Gull
14-15.5 Kelp Gull (S. America)
14-16 Belcher’s Gull
15-17 Olrog’s Gull
Underwing Color
Wing-tip Color and Pattern:
–Western Gull to note lack of sharp delineation of black wing tips from upper wing color
–Herring Gull to note sharp black wing tip delineation and areas of white wing tips
–Thayer’s Gull upper and under wing photo
–California Gull showing extensive black wing tips with sharp contrast
–Ring-billed Gull showing very contrasty look from light mantle to extensive black tips.
-See Black-legged Kittiwake photo above again.
For the rest of the sections above photos are good to recheck for these features.
–