NORTH AMERICAN GULLS AND THEIR ALLIES. 



63 



During Buturlin's stay at the mouth of the Kolyma River he paid 

 particular attention to Ross's gull and obtained definite information 

 in regard to the extent of its breeding range. It is known to breed 

 northwest to Russkoe Ustje, in the delta of the Indigirka River, 

 latitude 71° N., longitude 149° E.; southwest to Abyi, near the 

 Indigirka River, about 300 miles inland from the Arctic coast, latitude 

 67° 30' N., longitude 145° E.; northeast to the northeastern part 

 of the Kolyma delta near the Arctic coast, latitude 69° 30' N., 

 longitude 161° E.; and southeast to Sredne-Kolymsk, on the Kolyma 

 River, about 200 miles from its mouth, latitude 67° 30' N., longi- 

 tude 155° E. The breeding range extends, therefore, through 3| 

 degrees of latitude and 16 degrees of longitude, covering an area a 

 little less than 300 miles square. The species has not been found 

 breeding on any of the Arctic islands either east or west of the Kolyma 



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O OCCURRENCE 



Fig. 30. — Ross's gull (Rhodostcthia rosea). 



delta, but all these islands are rocky, while Ross's gull is exclusively 

 a marsh breeder. 



An interesting habit of this gull is its early desertion of its breeding 

 grounds. Only 20 days after the first egg hatched, both old and 

 young left the interior of the delta, and four days later the last one 

 disappeared from the coast at the mouth of the river. 



If the 60,000 square miles near the mouth of the Kolyma River 

 really comprise the only nesting place of this gull, then many non- 

 breeding individuals must spend the summer far from the breeding 

 grounds. The type specimen was taken in the height of the breeding 

 season, June 23, 1823, at Alagnak, Melville Peninsula, near Igloolik 

 (Ross). A second was seen there four days later, but the birds 

 were certainly not breeding anywhere in this region, for these are 

 the only individuals recorded in the vast stretch of 2,000 miles 

 between Greenland and Point Barrow. Birds presumably non- 

 breeders were noted by naturalists of the Jeannette just west of 

 Wrangell Island, June 22-30, 1880; one at Pitlekaj, July 1, 1879 



