516 GULL TRIBE. 



species, the glaucous gull (L.glaucus), in which the males may measure fully 32 inches, 

 is readily distinguished by the adult summer-plumage being nearly white through- 

 out, as well as by the comparative shortness of the wings and feet. Essentially an 

 Old World Arctic bird, this gull only wanders in winter to temperate and tropical 

 Europe ; while in the North Pacific it is represented by the allied L. glaucescens, 

 ranging from America to Kamschatka, and distinguished by the faint grey 

 mottlings on the wings. Another occasional wanderer to the British Isles from 

 the north is the Iceland gull (L. leucopterus), which may be distinguished from the 

 last by its length not exceeding 22 inches, and likewise by the proportionately 

 much longer wings and legs. Bonaparte's gull (L. Philadelphia), a small species 

 with a greyish black head and upper neck, is remarkable for its habit of breeding 

 in tall trees. 



Represented only by the common circumpolar kittiwake (Rissa 

 tridactyla) and an allied North Pacific species (R. brevirostris) from 



KITTIWAKES NESTING. 



the region lying between Alaska and Kamschatka, these gulls are distinguished by 

 the shortness of the metatarsus and the absence or rudimentary condition of the 

 first or hind-toe. It is not a little curious that while in most districts examples of 

 the common kittiwake in which the latter toe persists are but rarely met with, in 



