26 Dwight, The White-winged Gulls. [JjJ 



STATUS AND PLUMAGES OF THE WHITE-WINGED 

 GULLS OF THE GENUS LARUS. 



BY JONATHAN DWIGHT, JR., M. D. 



Plate I. 



In nearly all of the many species of gulls so widely distributed 

 in both hemispheres, the primaries are black variously patterned 

 with white or gray, but there are several species, Arctic in their 

 distribution, which may be set apart from the others by the white- 

 ness or pale coloration of these feathers at all stages of plumage. 

 The best known of these is the Glaucous Gull or Burgomaster 

 (Larus glaucus), the adult of which is a large bird, snowy white 

 except for the pale pearl-gray mantle, the color running over into 

 the primaries and fading out to white towards their apices. This 

 species is circumpolar, but Alaskan specimens, averaging a trifle 

 smaller, have received a name, the Point Barrow Gull (Larus 

 barrovianus) . Confined chiefly to the Arctic regions lying between 

 Spitzbergen and northern Canada is a small edition of the Burgo- 

 master, — the Iceland or White-winged Gull (Larus leucopterus) . 

 Less Arctic in distribution and found breeding on the Pacific 

 coast of North America, from the United States northward, is the 

 medium-sized Glaucous-winged Gull (Larus glaucescens) which 

 in a measure forms a connecting link between the white-primaried 

 species just mentioned and those having black primaries with 

 white spots. The mantle of this gull is much darker than that 

 of glaucus, and the primaries are slaty with terminal white spots. 

 Kumlien's Gull (Larus kumlieni) originally described from a 

 specimen taken on Cumberland Sound, and Nelson's Gull (Larus 

 nelsoni), taken in Alaska near St. Michaels, appear to be a 

 small and a large edition of the same species, the latter being 

 nearly the size of glaucus, the former about that of leucopterus. 

 Unlike either of the two, however, the primaries of both kumlieni 

 and nelsoni are more or less banded terminally or edged with 

 slaty markings. The status of both is open to some doubt, for 

 specimens are rare. Intergradation between them seems proba- 



