Measurements of Pacific Northwest Gulls

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.