80 BULLETIN 113, UNITED STATES NATIONAL MUSEUM. 



The birds had used a diversity of sites, some being on rocky peninsulas, others 

 on the turf back from the sliore, and many among bowlders or beside stumps a 

 short way from the water line. All seemed to have been situated with a view 

 to affording the owners a clear outlook, it being noted that apparently no birds 

 had selected locations beneath the canopy of the thicket or under the low, spread- 

 ing branches of spruces. 



Eggs. — The great black-backed gull lays usually three eggs, but 

 sometimes only two. The ground color varies from " pale olive buff " 

 to " wood brown," " buffy brown," or " Isabella color," with a tend- 

 ency in some specimens toward " tawny olive " or " cinnamon." They 

 are more or less heavily spotted or blotched with various shades of 

 brown, varying from " Brussels brown " to " clove brown," and are 

 often more or less spotted or clouded with pale lilac, drab, or lavender 

 gray. The measurements of 59 eggs, in various collections, average 

 77.9 by 54.2 millimeters ; the eggs showing the four extreme measure 

 86.5 by 54.5, 79 by 57.5, 73 by 53, and 73.5 by 51 millimeters. 



Young. — The period of incubation is said to be 26 days. Both 

 sexes incubate and assist in the care of the young. The young re- 

 main in the nest for a day or two, but are soon able to crawl out and 

 run about. They spend much of their time hiding in the grass, in 

 crevices between stones, among the underbrush, or anywhere that 

 they can find a little shelter, where they probably sleep most of the 

 time; but when disturbed they can run with surprising swiftness. 

 I have had to exert myself to the utmost to catch one of the larger 

 5'oung, whose long legs could carry it about as fast as I could run. 

 They are fed by their parents on soft, semidigested food at first, but 

 gradually they are trained to accept more solid food. Mr. Cleaves 

 has sent me the following notes on the feeding process : 



Young of all ages spent much energy in beseeching their parents for food, 

 and the old birds often displayed a discouraging apathy toward their young at 

 such times, even taking to flight or swimming away from the shore to escape the 

 entreaties of their progeny. The older youngsters would sometimes swim 

 after their parents in their eagerness for rations. In begging for a meal it 

 was usual for a young gull to utter a whining cry and to run his bill along the 

 neck or body of his parent. Not infrequently two or three young were thus 

 besieging one old bird simultaneously. 



In delivering food to her young the old gull first threw her head forward 

 and downward (with a deliberation of movement which must have been pain- 

 ful to the waitiug babies), then opened her spacious mouth and began a series 

 of contortions with her neck muscles. The youngsters, being well aware by now 

 of the imminent, centered attention on the flat stones in front of their mother, 

 where the disgorged dainties presently appeared. Both parents were observed 

 to feed the young. Immediately after delivering a meal the old birds some- 

 times stood by until the young were well underway with it — this so far as we 

 could see, being for the purpose of keeping off neighbors, either young or 

 old, who might be inclined to piracy. On one occasion an old bird chased into 

 tho wfter a half-grown youngster belonging to another pair, and, with her 

 blows at the back of his head with her beak, might have murdered him had 



