3/0 Dixon, Migration of the Yellow-billed Loon. [oct 



we came across individual birds in the dense forest. In October was not 

 nearly so common . 



85. Ixoreus naevius naevius. Varied Thrush. — Rather common 

 being found distributed in the forest fairly adjacent to the lake, but less 

 so up the mountain side. Its delightful song was heard each day in May, 

 especially at morning and evening and during the rainy and misty weather, 

 being in perfect harmony with its wild environment. Also commonly 

 seen in October. 



MIGRATION OF THE YELLOW-BILLED LOON.i 



BY JOSEPH DIXON. 



The lack of information relative to the migration routes of the 

 Yellow-billed Loon {Gavia adamsi) has been shown most forcefully 

 in Professor W. W. Cooke's interesting article in * The Condor ' 

 (vol. XVII, 1915, pp. 213-214). 



The tentative theories advanced by Cooke, await, of course, 

 the support or contradiction of further data, and certain field 

 observations of the writer are here set down as a possible contribu- 

 tion toward the ultimate solving of the problem. 



The Harvard Alaska-Siberia Expedition, of which I was a mem- 

 ber, was obliged, on account of unfavorable ice conditions, to 

 spend considerable time in 1913 and 1914 in what, according to the 

 A. O. U. ' Check-List ', is supposed to be the center of the breeding 

 range of this species, the Arctic coast of x\laska between Point 

 Barrow and the mouth of the Mackenzie River. This expedition 

 was financed in part by Mr. John E. Thayer, to whom the writer 

 is indebted for permission to use such of the information obtained, 

 as is needed in this paper. 



We naturally observed the arrival of the Yellow-billed Loons 

 with interest, and, during the time we spent there, especial atten- 

 tion was given to the loons in general, in the hope of finding an 

 authentic nest of the Yellow-bill. Not only did we fail to find any 



1 Contribution from the Museum of Vertebrate Zoology of the University of California. 



