LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS. 29 



Family LARIDAE, Gulls and Terns. 



PAGOPHILA ALBA (Gtmnerus). 

 IVOKT GULL. 



HABITS. 



This beautiful, snow-white gull of the Arctic regions is decidedly 

 boreal in summer and seldom wanders far south even in winter. It 

 is circumpolar in its distribution and has been noted by nearly all 

 Arctic explorers in both hemispheres. The names " ice-partridge " 

 and " snow-bird," which are applied to this species, are both very 

 appropriate, for the bird lives almost constantly in the vicinity of 

 ice and snow, where its spotless plumage matches its surroundings. 

 It is largely a bird of the open polar seas, frequenting the edges of 

 the ice floes in company with the fulmars and other Arctic sea birds, 

 and seldom resorting to the land except during the breeding season. 



Nesting. — Prof. Robert Collett (1888) has given us a very good 

 account of the nesting habits of the ivory gull, based on information 

 f uinished by Capt. Johannesen, who visited a breeding colony on the 

 small island of Storoen, near Spitzbergen, in 1887. I quote from his 

 excellent paper, as follows : 



On the 8th of August, when he visited the island, he found young birds in all 

 stages, from newly hatched to fully fledged, together with a small number of 

 eggs, which, however, were on the point of hatching, and in all probability not 

 one would have been left a week later. StorSen is about 9 English miles in 

 length and 6 in breadth ; the greater part of its surface is covered by a glacier, 

 which rises to a height of about 400 feet; the remaining portions consist of 

 sand and gravel, with here and there small stones, likewise oases covered with 

 moss ; while in a few places the ground consisted only of rock. 



L. eburneus was breeding on the northeast side of the island, close to, or 

 only a short way above, high-water mark, on low-lying ground like L. canus, 

 L. fuscus, etc., and not in the cliffs. Capt. Johannesen estimated the number 

 of nests at from 100 to 150; they were somewhat apart, at distances varying 

 from 2 to 4 yards. There were one or two eggs or young, but never more in a 

 nest. On being examined at Tromso it was found that all the 19 eggs contained 

 almost fully developed young chicks. Many of the nests contained young of 

 various ages, whilst others were already empty. Several black-spotted young, 

 capable of flight, were seen, likewise several young birds of the previous year's 

 brood remained on the breeding ground. The nest is composed chiefly of green 

 moss, which forms about nine-tenths of its mass. The rest consists of small 

 splinters of driftwood, a few feathers, single stalks, and leaves of algae, with 

 one or two particles of lichen. No trace of straw is to be found ; a couple of 

 pebbles may possibly have appertained to the underlayer of the nest. The 

 mosses occur in pieces the size of a walnut, or less, and have evidently been 

 plucked in a fresh state from a dry subsoil, either on rocks or gravelly places. 

 The mosses are all sterile. Several of the splinters of driftwood were found of 

 a length of about 100 millim. Under the microscope they all proved to be of 

 conifers, probably larch, drifted from the Siberian rivers. Some were very old ; 



