2A.O Rhoads on Vireo huttoiii insular is. I . ". 



Subsp. char. Colors as in Vireo huttoni, but much darker, being uni- 

 formly shaded over the whole plumage with a sooty suffusion. The oliv- 

 aceous buffy tints of huttoni nearly obsolete in insularis. Average 

 measurements slightly less than those of huttoni. Sexes alike. Young, 

 in nesting plumage, of similar colpr to huttoni. 



Measurements of the entire series were made in millimetres, 

 according to the system used by Mr. Ridgway in his 'Manual,' 

 except that all bill measurements were taken with dividers from 

 pit of nostril to tip of upper mandible. 



Wing Tail Bill 



Vireo huttoni, 60 (58-62) 50 (48-52) 6\ (5^-6|) 



stephensi, 65 (63-6S) 52 (49-54) 6-f (6 -?£) 



" " obscurus, 60 (60-61) 49 (4S-50) 64 (6 -6£) 



" " insularis, 61 (61-61) 49 (48-50) 5^ (5&-6) 



The favorite habitat of Hutton's Vireo and its conspecific allies 

 agrees closely with the sparsely wooded areas where the oak belt 

 overlaps the pine belt, and ranges in conformity with these floral 

 conditions from the sea level in the north to elevations of several 

 thousand feet in more tropical latitudes. The series in my custody 

 shows that this species is resident wherever found, and, with two 

 or three exceptions only, specimens taken south of the United 

 States in winter do not show close enough affinity to true huttoni to 

 indicate there is any migration of the northern forms into Mexico 

 or Lower California. It is interesting to note that the oaks, so 

 characteristic of the Pacific coast region, terminate rather abruptly 

 at the Columbia River, and, so far as I have personally investi- 

 gated the subject, are not found in the State of Washington. 1 On 

 the island of Vancouver, a species of oak {Qiiercus garryana) 

 reappears, and, according to Prof. Macoun, its range in British 

 Columbia is locally restricted to the southern part of that island. 



We find here a reproduction of all those conditions which seem 

 so indispensable to the presence of Hutton's Vireo in the south. 

 When we add to this the climatic conditions which have been so 

 notoriously conducive to the development of dark races on the 

 Northwest Coast, with the isolation of insularis from the nearest 

 habitat of huttoni and its permanent residence on the island, its 

 differentiation becomes almost a foregone conclusion. 



"'California to Oregon and British Columbia." Sereno Watson, Geol. Cala., Vol. II. 

 "San Francisco Bay to Puget Sound." Green and Kellogg in W. Amer. Oaks, 



