ICELAND-GULL 183 



much smaller than those of the glaucous-gull. The average of 46 

 eggs is 2'69 x T89 in. [68'4 x 48*1 mm.], and in ground-colour they vary 

 from light olive and grey-buff or greenish, to olive-brown, blotched 

 and spotted somewhat evenly with dark umber-brown markings, and 

 grey- violet underlying blotches. In some eggs the blotches and spots 

 tend to form a wreath. All detailed information as to the share of 

 the sexes in nest-building and incubation, as well as the length of 

 the incubation period, is still lacking. The eggs, in Greenland, are 

 generally laid between May 25 and June 28. 



The young of this species pass through similar stages of plumage 

 to those of the glaucous-gull, but the pure white stage, which has been 

 rarely met with in the case of the glaucous-gull, on account of its brief 

 duration, was unknown in this bird until described by Eagle Clarke 

 in the Proceedings of the Royal Physical Society of Edinburgh, 1899, p. 164, 

 and, as in that species, is only retained for a short time, just before 

 maturity is attained in the fourth year. 



Like the other large gulls, it is practically omnivorous, and in the 

 Arctic regions subsists largely on carrion, the excrement of large 

 mammals, and wounded or injured birds. It also devours fish, 

 molluscs, and crustaceans, and Saxby notes that it is more partial to 

 vegetable food than some of its congeners, often resorting to the 

 fields, where it is seen in attendance on the tethered pigs, possibly in 

 search of worms. The stomachs of birds examined by him contained 

 oats, vegetable fibre, and quartz. Faber states that in Iceland they 

 come to the house doors in winter to pick up the entrails thrown away 

 by the inhabitants, and fight fiercely for them with the ravens. To 

 the seal-hunters they are useful as indicating where seals may be 

 found, by continually pursuing them overhead as they swim below, 

 hovering over them while in pursuit of fish, and swooping down 

 upon their prey when driven to the surface. In the same way they 

 will follow the track of the cod-fish, to feed upon the fish and other 

 organisms pursued by them. On the whole, it may be described as 

 more of a fish-eating gull than a flesh-feeder. 



