650 HISTORY OF THE 



other two it is so distributed that over half the surface is con- 

 cealed by it. Of the specimens in the National Museum Collec- 

 tion, some are scarcely marked at all, while in others the ground 

 color is nearly hidden. The single egg found in the second 

 nest measures . 92x.69. This nest measures three inches in 

 depth by four inches in width, the central cavity being two inches 



deep." 



Turdus ustulatus swainsonii (CAB.). 



OLIVE-BACKED THRUSH. 

 PLATE XXXV. 



Migratory; common. Arrive about the first of May; begin 

 to return early in September; a few remaining late in October. 

 B. 153. K. 4a. C. 13. G. 4, 330. U. 758a. 



HABITAT. Eastern North America; north into the Arctic re- 

 gions; west to' and including the Rocky Mountains, and from 

 the upper Columbia River northwest throughout the wooded 

 lands of Alaska; breeding chiefly north of the United States; 

 wintering from the Gulf States southward into northern South 

 America. 



SP. CHAR. Adult: Above, uniform olive brown, more grayish in some ex- 

 amples; a very distinct orbital ring of buff; supraloral stripe, malar region, 

 chin, throat and jugulum light buff, usually deepest toward sides of head and 

 neck; jugulum thickly marked with very broad triangular spots of dusky brown 

 (much darker than the color of the crown), these markings more cuueate ante- 

 riorly, and continued along sides of throat in a series of longitudinal dashes, 

 usually blended into a more or less continuous submalar stripe, narrower and 

 unbroken anteriorly; chin and upper parts of throat immaculate; sides of breast, 

 sides and flanks olivaceous gray; rest of lower parts pure white; breast marked 

 with distinct transverse spots of deep brownish gray; tibia light brownish gray. 

 Axillars and lining of wing deep grayish fulvous, mixed with ochraceous. (Ridg- 

 way.) 



Stretch of 

 Length. -wing. Wing. Tail. Tarsus. Bill. 



Male 7.40 12.15 4.00 3.00 1.12 .52 



Female... 7.15 11.65 3.80 2.80 1.10 .50 



Iris brown; bill dusky, with under pale straw color at base; 

 legs pale brown; feet and claws a shade darker. 



This species is more a bird of the woods than the Gray- 

 cheeked Thrush,* which it so closely resembles in build, color, 



*From the observations and collections made on the upper Yukon, the Olive-backed 

 Thrush appears to be a common summer resident there, and thus ex ends its breeding range 

 within the Arctic circle. It appears to be influenced to a great extent in its ange by the pres- 

 ence or absence of woods, and its northern limit may be marked as coinciding with the tree 

 limit. Alicia, on the contrary, extends beyond this, wherever a bunch of dwarf willows will 

 give it shelter, to the very shores of the Arctic and Behring Seas. ( Nelson. ) 



