90 University of California Publications in Zoology [yoL. 21 



In a study of geographic variation in these birds there are some 

 features deserving of the strongest emphasis. Before proceeding with 

 an analysis of the above indicated divisions it is advisable briefly to 

 summarize certain of these important points, the details of which are 

 dwelt upon at length further on in this paper. Fox sparrows belong- 

 ing to what I have termed the Unalaschcensis group occur on the 

 Pacific coast of North America, from the Alaska Peninsula to Puget 

 Sound, in practically continuous distribution. From the northern 

 extremity of this narrow coastal strip to the southern, definite lines 

 of variation may be traced without a break. Beginning at the north, 

 with the large-sized, large-billed, and pale colored unalaschcensis, there 

 is a series of gradual changes to the southward culminating in 

 the small-sized, small-billed, and extremely dark reddish townsendi. 

 Farther south, fuUginosa, though still darker colored, shows some 

 increase in size. Between the extremes there are birds exemplifying 

 several well-defined, intermediate steps, occurring within definitely 

 circumscribed areas, and recognized as separate subspecies. Between 

 each two abutting races intergrades occur ; it is of common occurrence 

 to find individuals so exactly intermediate between any two geo- 

 graphically adjacent subspecies of this group that their allocation 

 must be rather arbitrarily determined. 



There is here distribution of a bird species that is presumably 

 continuous in part (upon the mainland), and is discontinuous in the 

 occurrence of the birds upon the many islands along the coast. One 

 strongly marked island subspecies has resulted, insularis, upon Kadiak 

 Island. As in no other instance has similar insulation resulted in the 

 production of distinguishable races upon other islands, it is conse- 

 quently questionable to what extent insularis owes its strongly marked 

 characteristics to this cause. On the contrary, we see sinuosa occur- 

 ring on several islands and on the nearby mainland, with no differ- 

 entiation. A still stronger example is afforded in townsendi, which 

 occurs on the mainland, on several, if not all, of the islands of the 

 Alexander Archipelago, and on the relatively remote Queen Char- 

 lotte Islands, practically unchanged throughout this disconnected 

 habitat. This is still more striking when we consider the differentia- 

 tion that has arisen in other bird species upon the Queen Charlotte 

 Islands. This differentiation in the cases of the Queen Charlotte 

 hairy woodpecker (Dryohates villosus picoideiis) and the Queen Char- 

 latte jay {Cyanocitta stcUeri carlottae) is a darkening of color as 

 compared with their nearest relatives, and considering that the trend 



