576 



Averill, Migration and Physical Proportions. 



rAuk 

 |Oct. 



Of these eight geographical races the longest migration is made 

 by the Northern Yellow-throat which has the shortest tail in re- 

 lation to wing. It is important to notice that the southern, 

 western and Mexican birds are all longer tailed with the exception 

 of the salt marsh race. We often read in the text books that 

 western races have longer tails, but it is seen in this table as well 

 as in the others that it is the bird of limited range that has this 

 characteristic, rather than the bird of any particular region. 



It will be of interest to tabulate the whole genus Dendroica on 

 account of the number of species and because we have great dif- 

 ferences in length of annual journeys — from thousands of miles 

 each year to zero. 



Dendroica I. Breeding in Hudsonian and Canadian Zones. 

 Winter in South America. 



Blackpoll Warbler 

 Bay-breaste<l 

 Blackburnian 

 Yellow 



In 



Average 



Dendroica II. Breeding in Southern States. Winter in S. A. 



W. T. Diff. Culm. Tars. 

 Cerulean 65.5 45.0 20.5 9.9 16.5 



Dendroica III. Alaska to Labrador. Not breeding S. of 



Canadian zone. Wintering U. S. to Panama. 



Myrtle 74.1 56.2 17.9 10. 19.6 



