88 BULLETIN 113, UNITED STATES NATIONAL MUSEUM. 



Eggs.— These two sets might easily be matched with eggs of some 

 of the commoner species of Larus. The shape is practically ovate and 

 the ground color is " Isabella color." They are more or less evenly 

 covered with small spots of "clove brown," "blackish brown," 

 " sepia," and "bister," as well as several shades of" brownish drab." 



Two eggs in the writer's collection, from the Asiatic coast, show 

 other extremes of coloration. The darker one has a ground color of 

 " Saccardo's umber" and is spotted with "blackish brown" and 

 " brownish drab ;" the lighter one has a " deep olive-buff " ground 

 color and is spotted with " snuff brown," " bister," and several shades 

 of " brownish drab," some very light and some very dark shades. 

 The measurements of 34 eggs, in various collections, average 74 by 

 51.5 millimeters; the eggs showing the four extremes measure 

 81 by 52, 77 by 54, 67.1 by 50 and 72 by 48 millimeters. 



Plumages. — I have never seen the downy young of this species, nor 

 can I find any description of it in print., The sequence of molts 

 and plumages, so far as can be learned from the limited amount of 

 material available for study, is practically the same as in the great 

 black-backed gull. Young birds during the first fall and winter are 

 darker than those of the commoner species, particularly on the under- 

 pays, which are nearly uniform dusky. 



Behavior. — For the remainder of the life history of this little- 

 known species I must again quote from Mr. Buxton's notes, as 

 follows : 



After the nesting season is over, about the 1st of August, the breeders and 

 young of the year join the nonbreeders and they all spend the rest of the season 

 in flying up and down the river, collecting in large flocks along the water fronts 

 and gorging themselves on the worn-out, salmon that they find there. At this 

 time they begin to fly up the river at 2 or S o'clock in the morning, continuing: 

 to fly until the middle of the forenoon, and then begin the return flight at 5 p. m., 

 and continue to fly until long after dark, which does not occur at that time 

 until 10 or 11. p. m. -They are so abundant that on these flights there is one 

 continuous long, loose flock of. them without any considerable break or inter- 

 mission. The height of the return flight is from 6 to 8 p. m. When the wind 

 is strong they fly high, but when it is calm' they fly low and are easily attracted. 

 When one is killed on the wing, or a decoy is thrown Into the air, all the gulls 

 in the vicinity will immediately " land about " and circle once or twice over 

 the dead bird or decoy, changing their usual guttural cackle to hoarse " squeals" 

 of alarm before, proceeding on their way. I have often seen them attempt to 

 take a fish from the mouth of a seal when it arose to the surface and which the 

 gull had been watching catch the fish. By the 1 last of August one dark or 

 young one is seen to every four or five adult or white ones, and later the propor- 

 tion of the dark ones is much higher, as the adults begin to leave first. By the 

 1st of October the migration is well advanced, and decreases daily until by the 

 15th of October few remain, although the last of them do not leave until the 

 last week of the month. They are the last of the migrants to leave in the falL 



