ORNITHOLOGICAL EXPLORATIONS. . 3? 



gradual iucrease of the number and size of these plumes : 92979, 92984, 

 92983, 92982, 92981, 92978, 92980. 



Cousideriug that most of the above specimens were obtained during 

 the week between Christmas and New Year, the following conclusions 

 seem to be justified: 



The Least Auk, after the breeding season is over, probably at the 

 same time as the corresponding process takes place in the allied species, 

 loses the peculiar knob at the base of theculmen together with the length- 

 ened and pointed white plumes ornamenting its face and head. About 

 the end of the year, in some individuals earlier, in others later, a new 

 knob and new ornamental feathers grow out, and, shortly after, the 

 moult of the feathers of the body commences. The color of the bill also 

 begins to change at the same time. 



Dr. Dybowski asserts that he has found Gieeronia pusilla "nesting" 

 at the Commander Islands (" nistend," Orn. Centrbl., 1882, p. 28). He 

 gives no particulars, however, and during my subsequent sojourn on the 

 island I could learn nothing about it. One thing is sure, that he got no 

 eggs from there, and I doubt very much that the species has ever been 

 found "nesting" on the islands. The birds are unknown to the inhabi- 

 tants, at least to those of Bering Island, which I learned by showing them 

 my winter specimen. Nor have they any vernacular name for the bird. 

 In all probability Dr. Dybowski has been misinformed about the date 

 of his specimen, which, curiously enough, is not mentioned by Taczan- 

 owski in his lists of the birds from Kamtschatka. 



It was on December 1, 1882, that a specimen was brought me from 

 Ladiginsk, on Bering Island, It was in full winter plumage, entirely 

 white beneath, without knob, and with only a few traces of white 

 feathers on the face. A few days before the end of the year several 

 birds came near the shore, where they now could be seen to swim in 

 small troops, or more frequently by twos and threes, parallel to the coast 

 about a hundred yards oft" shore, according to the depth, usually in three- 

 fathom water, where they dived with great expertness for Amphipods, 

 which at that time seemed to be their chief or only food. When diving 

 they lifted themselves up a little, and went down with a quick jump. 



We were having a severe spell of cold when they made their appear- 

 ance, and when it was over they disappeared again, none being seen 

 after the 5th of January. They evidently winter on the open ocean 

 somewhere about the islands. 



