34 Beebe, The Early Life of Loon Chicks. [Auk 



so to speak, a graduated scale of regularly arising, cumulative 

 differences, but at their points of contact they are more unlike than 

 at their geographical extremes. 



We consequently are led to consider the possibility of the Yel- 

 low-throats having acquired their present range through some 

 such method of progress as the Grackles appear to have followed, 1 

 and an earlier stage of which the Loggerhead and Migrant Shrikes 

 exhibit. An apparently not dissimilar case is afforded by the Pa- 

 rula Warblers, in which the New England form is the same as that 

 found in the Mississippi Valley. 



In other words, Yellow-throats may have advanced from Florida 

 northward, and also from the Mississippi Valley eastward and 

 northward; when, as has been said, the Northern Yellow-throat 

 is not a direct geographical offshoot of the southern bird, although 

 both doubtless had a common point of origin. Intergradation, 

 therefore, is not necessarily climatic but follows actual contact 

 occasioned by extension of range. 



NOTES ON THE EARLY LIFE OF LOON CHICKS. 



BY C. WILLIAM BEEBE. 



Curator of Ornithology, New York Zoological Society. 



Plate II. 



On August 4, 1906, two eggs were taken from the nest of a 

 Loon, Gavia imber (Gunn.), on a lake of the Muskoka District, 

 Ontario. The eggs were cold, and from observation it was judged 

 that the parents had deserted them some 48 hours previously. 

 Packed in a suit-case, the eggs were brought to New York City 

 and on the evening of August 6, one young loon hatched. The 

 following day this chick was brought to the New York Zoological 

 Park, together with the second egg, which was chipped. 



» CJ. Chapman, Bull. Am. Mus. Nat. Hist., IV, 1892, pp. 1-20. 



