LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS. 45 



range throughout the northern part of the northern hemisphere, 

 giving the species a circumpolar distribution. 



Spring. — The spring migration is early, reaching Bering Island, 

 in the Commander group, according to Stejneger (1885), about the 

 1st of April. In Bering Sea the migration is delayed until the 

 breaking up of the ice. Nelson (1887) says : 



At St. Michaels each year they arrive from the 10th to the 18th of May, and 

 were first seen searching for food in the narrow water channels in the tide 

 cracks along shore. As the open spaces appeared they congregated there until 

 in early June, when the ice broke up and moved offshore. At this time the 

 kittiwakes sought the rugged cliffs along the shore of the mainland or the 

 precipitous islands dotting Bering Sea and the adjoining Arctic. 



Courtship.— Very little seems to be known about the courtship or 

 mating performances of this bird, but Mr. H. W. Elliott (1875) says 

 that "the male treads the female on the nest, and nowhere else, 

 making a loud shrill, screaming sound during the ceremony." 



Nesting. — We saw plenty of kittiwakes near the eastern end of 

 the Aleutian Islands, where they were probably breeding in the 

 vicinity of Akutan Island. West of Unalaska we saw very few 

 birds and no signs of breeding colonies. Doctor Stejneger (1885) 

 found them breeding in " astonishing numbers " at certain places in 

 the Commander Islands, at the western end of the chain, where they 

 choose "steep walls, rising perpendicularly out of the deep sea, 

 and especially high pinnacles standing lonely amidst the foaming 

 breakers, provided they are fitted out with shelves and projections 

 upon which to place the nests." Dr. W. H. Dall (1873) gives us the 

 following good account of a breeding colony in the Shumagin Islands, 

 south of the Alaska Peninsula : 



On entering Ooal Harbor, Unga, we were at once struck with the peculiar white 

 line which wound around the precipitous cliffs of Round Island, and was seen 

 to be caused by the presence of birds ; and as soon as an opportunity was 

 afforded I took a boat and went to the locality to examine it. The nests, in 

 their position, were unlike anything I had ever seen before. At first it ap- 

 peared as if they were fastened to the perpendicular face of the rock, but on 

 a close examination it appeared that two parallel strata of the metamorphic 

 sandstone of the cliffs, being harder than the rest, had weathered out, stand- 

 ing out from the face of the cliff from 1 to 4 inches, more or less irregularly. 

 The nests were built where these broken ledges afforded a partial support, 

 though extending over more than half their width. The lines of nests exactly 

 followed the winding projections of these ledges, everywhere giving a very sin- 

 gular appearance to the cliff, especially when the white birds were sitting on 

 them. The nests were built with dry grass, agglutinated together and to the 

 rock in some unexplained manner; perhaps by a mucus secreted by the bird 

 for the purpose. The nests had a very shallow depression at the top in which 

 lay two eggs. The whole establishment had an intolerable odor of guano, and 

 the nests were very filthy. The birds hardly moved ,at our approach ; only 

 those within, a few yards leaving their posts. I reached up and took down two 

 nests, one containing two young birds, and the other empty. Wind coming up, 



