LIFE HISTORIES OF NORTH AMERICAN GUILLS AND TERNS. 87 



J. A. Allen (1905), give the best life history of the species in that 

 region. He writes: 



This is the most conspicuous and one of the most abundant birds along the 

 Okhotsk Sea. From the time of its arrival until it departs there is scarcely a 

 time when one can not either hear or see one or more of these birds. The first 

 arrivals are usually reported about the 20th of April, and from that time on 

 they increase in numbers daily until May 1, when they have nearly all arrived. 

 From the time of their arrival until the nesting season begins they make daily 

 excursions up the rivers in the morning and return to their roosting places 

 along the seacoast in the evening. They go up the Gichiga River at this time 

 as far as Christova, 30 miles above its mouth. Also at this time many may 

 be seen soaring in large circles high over the tundra and marsh above the mouth 

 of the river, Mhen they utter a cry very similar to that of the red-tailed hawk 

 during the breeding season. None of the dark phase are seen among the earlier 

 arrivals, but by the 15th of May they begin to appear, and increase in numbers 

 until they have all arrived, although at no time during the spring and early 

 summer do they form any considerable per cent of the thousands that one sees. 

 Before the ice goes out of the head of the bay and river, their food supply is 

 limited to the few dead salmon which the melting snow exposes on the gravel 

 bars along the river beds and the mussels they pick from the rocks along the 

 seacoast at low tide. 



Nesting. — By the first of June all of the breeders have repaired to the rugged 

 seacoast and rocky islets lying off it, below the mouth of the river, to breed. 

 Only the roughest and most inaccessible places are chosen for nesting sites, 

 generally at the headlands, where sections of the solid rocks have been partly 

 or wholly separated from the mainland. The nests, which are loose, bulky 

 structures, composed of grass and with but a slight depression in the center, 

 are placed on ledges and the tops of rocks. Three eggs constitute a set, and 

 they show the usual large variation in color and size found in the eggs of 

 other species of Larus. The height of the nesting season is reached about June 

 10, when the koraks visit their rookeries and obtain large numbers of their 

 eggs by being lowered down the cliffs with sealskin lines. Many more breeders 

 spend the summer on the bars and along the marsh near the mouth of the 

 river, and on the gravel bars along its bed. 



Rev. W. F. Henninger (1910) refers to three sets of eggs of the 

 slaty-backed gull, containing three, two, and one eggs, respectively, 

 that were " taken on the coast of Siberia, near the Bering Strait, on 

 June 4, 1905. The nest was a mere depression or hollow in some 

 moss." There are two sets, of three eggs each, in Col. John E. 

 Thayer's collection, taken by Capt. H. H. Bodfish in Harrowby Bay, 

 on the Arctic coast of northwestern Canada, June 11, 1901. The nests 

 are described as made of grass, roots, and mud and lined with dry 

 grass; they were placed on a point making into the bay. The parent 

 birds were collected and the skins were identified by Mr. Robert 

 Ridgway and Dr. A, K. Fisher- These are probably authentic sets, 

 though they were taken outside of the previously known breeding 

 range of the species, 

 174785—21 7 



