Species are arranged in decreasing order of size (weight). Each set of measurements is expressed in millimeters, with mean length of males followed by range of males and females. Sample sizes (6-15) are small, and the ranges given may be exceeded in most if not all species. Note the substantial overlap in many species of similar size, especially because females are distinctly smaller than males. All measurements are taken from The gulls (Laridae) of the World, by Jonathan Dwight, Bull. Amer. Mus. Nat. Hist. 25, 1925.
* Very rare to accidental species are asterisked.
Measurements of Pacific Northwest Gulls
| Species | Wing Length | Bill Length | Bill Depth | Bill Depth/Length |
|---|---|---|---|---|
| Great Black-backed Gull* | 481 (454-498) |
64.8 (57-72) |
25.0 (22-27) |
0.386 |
| Glaucous Gull | 459 (430-477) |
62.6 (56-67) |
22.4 (18-25) |
0.358 |
| Glaucous-winged Gull | 423 (385-445) |
57.6 (49-64) |
20.6 (18-22) |
0.358 |
| Western Gull | 412 (384-420) |
55.6 (49-58) |
21.2 (17-22) |
0.381 |
| Slaty-backed Gull* | 440 (405-447) |
58.7 (49-60) |
20.6 (18-22) |
0.351 |
| Herring Gull | 434 (397-460) |
57.0 (47-62) |
20.3 (17-22) |
0.356 |
| Lesser Black-backed Gull* | 412 (382-428) |
53.1 (44-56) |
17.8 (15-19) |
0.335 |
| Thayer's Gull | 418 (380-430) |
52.2 (43-57) |
18.1 (15-20) |
0.347 |
| Iceland Gull* | 412 (378-433) |
42.6 (39-45) |
15.6 (14-17) |
0.366 |
| California Gull | 399 (368-415) |
50.0 (42-56) |
16.9 (14-20) |
0.338 |
| Ring-billed Gull | 377 (335-392) |
42.4 (36-46) |
14.0 (12-16) |
0.330 |
| Heermann's Gull | 347 (329-368) |
43.7 (37-48) |
14.1 (12-15) |
0.323 |
| Ivory Gull* | 338 (320-346) |
35.9 (32-38) |
12.1 (10-13) |
0.337 |
| Mew Gull | 351 (328-366) |
35.4 (30-38) |
10.8 (9-12) |
0.305 |
| Black-legged Kittiwake | 310 (295-320) |
37.9 (34-40) |
11.0 (10-12) |
0.290 |
| Red-legged Kittiwake* | 305 (290-310) |
28.6 (26-30) |
10.7 (10-11) |
0.374 |
| Laughing Gull* | 321 (295-330) |
40.2 (35-44) |
11.3 (10-12) |
0.281 |
| Franklin's Gull | 277 (262-286) |
30.7 (27-34) |
9.0 (8-10) |
0.293 |
| Black-headed Gull* | 312 (280-325) |
36.8 (32-39) |
9.3 (8-10) |
0.253 |
| Bonaparte's Gull | 263 (246-271) |
29.9 (27-32) |
7.0 (6-8) |
0.234 |
| Sabine's Gull | 267 (245-284) |
25.5 (22-28) |
7.6 (6-8) |
0.298 |
| Ross' Gull* | 255 (248-265) |
19.3 (18-20) |
6.1 (5-7) |
0.316 |
| Little Gull | 221 (210-230) |
23.2 (21-25) |
5.5 (5-6) |
0.237 |
Although wing length is correlated with body size, it is also correlated with other attributes of the bird such as long-distance flying (both foraging and migration). Similarly, bill size is correlated with feeding mode. Thus the birds are not exactly in order of decreasing wing or bill length. The larger the figure in the bill depth/bill length column, the relatively deeper the bill.