LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS. 33 



tipped with dusky, narrowly edged with white. As to how long this 

 plumage is worn or at what age the adult, pure white plumage is 

 acquired, I am in doubt. Selby (1833) says: 



As the bird advances in age the brown spots and bars gradually decrease at 

 each molt, and it is supposed to be perfectly matured in two years and a half. 



I very much doubt if it requires any such time as two years to 

 reach maturity, and I have never seen a bird with any spots on it at 

 all, except a few on the edge of the wing, which I thought was over 

 a year old. Probably the dusky tips wear away somewhat during 

 the winter or are partially replaced by white feathers at an incom- 

 plete prenuptial molt, and at the first postnuptial molt the pure 

 white adult plumage is assumed ; but, unfortunately, I have not been 

 able to study sufficient material to determine this with certainty or 

 to understand fully the seasonal molts of adults. Adults ap- 

 parently have but one complete annual molt in July and August. 

 I have seen an adult which had not begun to molt its much-worn 

 plumage on July 3, and another, in fresh plumage, which had com- 

 pleted the molt on August 30. These are in the Dwight collection, 

 which also contains two specimens, taken July 6 and 13, molting 

 both wings and tails, and another, taken on May 30, in which the 

 wings are molting, beginning with the inner primaries. 



Food.^-The feeding habits of the ivory gull are hardly becoming 

 a bird of such pure and spotless plumage. It is a greedy and vora- 

 cious feeder and is none too particular about the quality of its food 

 or how it obtains it. When some of these birds have been feeding 

 on the carcass of a whale they present a sorry spectacle, for in their 

 eagerness to satisfy their gluttonous appetite they crowd them- 

 selves into the entrails of the animal and their beautiful white 

 plumage becomes smeared with blood. They are particularly fond 

 of the blubber and flesh of whales, walruses, and seals, even when 

 somewhat putrid, and, when busily engaged in such a feast they 

 are tame and unsuspicious. Nothing in the way of animal food 

 comes amiss to them and they even frequent the holes in the ice used 

 by seals for the purpose of feeding on the excrement of these ani- 

 mals. Pieces of meat, blood, or offal from slain animals scattered on 

 the ice or snow will always attract them. Any refuse thrown from 

 the galley of a ship is readily picked up. Mr. Kumlien (1879) says 

 that he once saw one try to swallow the wing of an eider, which the 

 cook threw overboard. They also feed to a large extent on lem- 

 mings and other small rodents. On their breeding grounds, in the 

 Polynia Islands, Captain McClintock (1856) found the bleached 

 bones of lemmings scattered about their nests, " also fresh pellets, 

 consisting of their bones and hair." 



