CALIFORNIA GULL 249 



On May 27, 1916, Mr. Dixon visited the nesting colony of California 

 Gulls on Paoha Island, the larger of the two islands in Mono Lake. (See 

 pi. 41.) From the north side of Paoha two ridges of black obsidian-like 

 rock extend northward about 200 yards out into the lake. These ridges 

 are about 20 feet high and enclose a long narrow bay about 10 or 15 yards 

 wide and 100 yards in length. Gulls nest on both of these peninsulas but 

 chiefly on the eastern one which bears a rather dense growth of a shrubby 

 plant. Here, over an area of II/2 to 2 acres, there was an average of at least 

 one nest for every 100 square feet; in some places it was estimated that 

 there was one to each 10 square feet. The total number of breeding birds 

 was believed to be close to 1000 pairs. 



The nests were placed on the rocky shingle of the beach, in depressions 

 under bushes and on the tops of rocks. Nesting material was scanty, 

 consisting chiefly of old wing feathers, molted in previous years. Many 

 mummified bodies of half -grown young of last year's brood were lying 

 about, and in one instance one of these mummies formed the principal part 

 of the nest. Nests containing 2 eggs were more common than those with one 

 or with 3 eggs, the latter occurring in about equal numbers. One nest 

 held 4 eggs, but this large number was clearly the result of two birds 

 laying in the same nest ; for 2 of the eggs were relatively short with a light 

 greenish ground color, while the other 2 were longer, more pointed, and of a 

 brownish ground color. Laying had evidently commenced about May 15, 

 for many of the eggs contained half-developed embryos, but none had yet 

 hatched. The parent gulls seemed to appreciate the need for sheltering 

 their eggs from the intense heat of the sun, which beat down on the bare 

 black rocks. They were often seen standing so as to cast a shadow over 

 their eggs, while they themselves held their mouths open and panted from 

 the heat. Males were seen whose actions seemed to show them to be urging 

 their mates to return to the nests ; in some instances they accompanied 

 the females when the latter returned to their duties. 



On July 3 a second visit was made to the Paoha Island colony. By this 

 time practically all of the eggs had hatched ; about one-third of the young 

 were running about, well feathered and almost half grown. Four nests 

 were found with chicks not more than a day old, and one contained a downy 

 gull so recently hatched from the egg that it was not yet dry. Despite its 

 recent emergence from the shell, this chick was able to scramble about until 

 it found shelter in the shade of a rock. Apparently the adult birds had 

 been more successful with their broods this year, for there were few dead 

 bodies of young gulls about and no infertile eggs. It is possible, however, 

 that abandoned or infertile eggs are promptly eaten hy neighboring mem- 

 bers of the colony. 



