100 BULLETIN U3, UNITED STATES NATIONAL MUSEUM. 



This species breeds in colonies, which in some places are very large, when 

 their nests are placed so close to each other, that it is by no means easy to 

 traverse their nursery without treading upon either the eggs or young. The 

 nest, if on the ground, is little more than a scraped out hollow in the ground, 

 lined with grass, seaweed, or herbage of any kind within reach ; if on a rock, 

 a larger pile of the same substances is bnilt up in the selected niche or ledge. 

 It is not at all uncommon to find the herring gull nesting in close proximity to 

 it, only, however, in the more inaccessible ledges or summits. Three eggs are 

 laid as a rule — four occasionally, sometimes only two — which vary very greatly 

 in size, shape, and color. Many of them are hardly, if ever certainly, to be 

 distinguished from those of the herring gull. They vary in size from 2§ 

 to 3 inches in length, by If to 2 in diameter. Ground color, from very pale gray, 

 through olive-brown to greenish-blue or chocolate-brown, spotted and blotched, 

 often more abundantly at the greater end, with black or dark brown. From 

 the end of May, through June and into July, eggs and chicks of all stages and 

 ages may be found. 



Eggs. — Rev. F. C. R, Jourdain has sent me the following measure- 

 ments of eggs of this gull from the British Isles : Eighty eggs aver- 

 age 68,04 by 47.39 millimeters; the eggs showing the four extremes 

 measure 77.1 by 49, 72.5 by 53.1, 58.6 by 45 and 61.3 by 43 milli- 

 meters. 



Young. — Doctor Forbes (1898) says of the young: 



After about three weeks' incubation the chicks break through their prison, as 

 lively and nimble balls of down, grayish-buf£ above, with the head, neck, and 

 back spotted with brown ; the under side paler and unspotted. On the least 

 intrusion on their cubicle tney are ready to be off — running, as Mr. Battye 

 remarks, head down and shoulders up like a falcon — to the nearest herbage or 

 water for security; but if left undisturbed they may be found for a fortnight 

 or more in the nest, most assiduously tended by the parents. The approach of 

 any intruder when the helpless young are in the nests is the signal to set the 

 whole of the colony on wing, wheeling round his head, swooping down upon 

 and screaming at him. 



Plumages. — When fledged, the bill, legs, and feet are livid corneous. The 

 feathers, which are white in the adult, have a center streak, or a bar of ashy- 

 brown, and pale edges; and where black they are reddish-brown, with yellowish- 

 white edges. The wing feathers are sooty or black, and the tail is mottled with 

 brown, which, near the end, becomes almost a continuous bar, the tips of the 

 feathers being grayish-white; the bill is horn color, and the legs and feet 

 brown i sh-whi te. 



During its first autumn the bird undergoes no true molt, but the brown 

 becomes less marked in some parts by loss of pigment, and more uniform 

 through the wearing ofE of the pale tips. In the next spring there is a more 

 general but slow molt, in which the brown comes in of a less deep shade, and 

 during the second autumn its color becomes a little paler still. During the next 

 year, in spring and autumn by feather-changes, and loss of pigment in them, 

 the brown is still further lost ; bill yellow at its base, but without the red spot 

 on the angle of the mandible. 



In the fourth autumn this gull has assumed almost the complete winter dress 

 of the adult — the white spot near the end of tlie primaries perhaps alone not 

 being well marked. The following spring, when the bird is in its fifth year, 



