LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS. 55 



On June 15, near St. Michaels, another nest was found, an equally conspicuous 

 structure. Like the majority of their nests found by me, it also was located 

 on a small islet in a pond. It was 2 feet high, with a base from 3 to 4 feet long by 

 2 wide and measured about IS inches across the top. In the apex was a de- 

 pression about 5 inches deep and 9 inches in diameter. This bulky structure 

 was made up of tufts of moss and grass rooted up by the birds' beaks. The 

 ground looked as though it had been rooted up by pigs in places near the nest 

 and on the outer edge of the pond ; and while I was examining the nest, which 

 contained three eggs, one of the old birds came flying iip from a considerable 

 distance, carrying a large tuft of muddy grass in its beak and dropped it close 

 by on seeing me. One of the eggs taken was white, without a trace of the 

 usual color marks. While I was securing the eggs the parents swooped down 

 close to my head, uttering harsh cries. 



On July 7, 1911, I visited Walrus Island, in the Pribilof group in 

 Bering Sea, where among all the hordes of water fowl that breed in 

 this wonderful islet was a nesting colony of glaucous-winged and 

 glaucous gulls. Their nests were scattered among the tufts of short, 

 coarse grass, which covered the highest and central part of the 

 island, where soil had been formed by the accumulation of guano. 

 The nests were rather bulky and well made of seaweed and soft 

 grasses; a few of them still contained eggs, but nearly all of the 

 young had hatched and were hiding in the grass and among the 

 rocks. We were not allowed to shoot any birds here and the gulls 

 were too shy to enable us to identify any nests, but I am positive 

 that both species were breeding here. The glaucous-winged gull 

 seems to have been overlooked by some of the others who have visited 

 this island, though it may not have been breeding there then. 



Eggs. — As with most gulls, only one brood is raised in a season 

 and the set usually consists of three eggs, though two eggs frequently 

 complete the set. The eggs are similar to those of other large gulls, 

 varying in shape from ovate to elongate ovate. The shell is rather 

 coarselj'' granulated and without luster. The ground color shows the 

 usual variations from " buify brown " to " deep olive buff " or " pale 

 olive buff." The eggs are usually not very thickly and more or 

 less irregularly spotted with small spots or blotches of various 

 shades of the darker browns, such as " bone brown," " bister," or 

 " Saccardo's umber " ; also sometimes with lighter browns and often 

 with underlying spots of various shades of the lighter drabs and 

 lavender grays. The measurements of 56 eggs in the United States 

 National Museum average 75.8 by 52.4 millimeters; the eggs showing 

 the four extremes measure 85.5 by 50.5, 78 by 57, 70 by 52.5 and 76.5 

 by 48 millimeters. 



T oung. —Qoi\i Turner (1886) and Elliott (1875) give the period of 



incubation as about three weeks, but probably four weeks would be 



more nearly correct ; Evans (1891) gives it as 28 days. Probably both 



sexes incubate, for the pairs keep together at this time, and the male 



174785—21 5 



