BIRDS OF MINNESOTA 439 



TLRDUS USTULATUS SWAINSONII (Cabanis). (758a.) 



OLIVE-BACKED THRUSH. 



The uniform shade of the upper parts, somewhat emphasized 

 on the rump and tail, distinguishes this species amongst the 

 Thrushes. 



Arriving here late in April, or in the early part of May, it is 

 abundant for a short time, but moves northward then, only a 

 few comparatively remaining to breed, and those principally 

 in the northern counties of the State. Its favorite places for 

 nesting here seem to be the edges of heavy timbered tracts, 

 which are bordered with brushland, or thickets of oaks. They 

 build their nests about the 20th to the 25th of May, on a hori- 

 zontal limb, which is usually five to seven feet from the ground. 

 It is very compactly built of such material as the locality af- 

 fords including strips of bark, leaves, lichens, moss, &c. The 

 eggs, usually four or five in number, are light greenish-blue, 

 speckled with several shades of reddish -brown. 



The song of this species does honor to its melodious group, 

 having about as much variety as those of the other thrushes, 

 and more nearly resembles that of the Hermit. For many years 

 Swainson's Thrush was seldom seen except in migration, but 

 since the country has been more extensively settled, and fires 

 have ceased to destroy the brushlands and timber, it has been 

 increasing in the numbers of individuals that remain during 

 the summer. I have seldom found it feeding on the ground 

 after the manner of most of the same genus but on the trees 

 and brush, and unlike any of them, dashing out after insects 

 essentially like a warbler or a flycatcher. 



One specimen of this species obtained in July was building a 

 new nest, which must be exceptional, for although rearing two 

 broods they appear usually to build but one. Perhaps it had 

 been molested. The autumnal migration takes place simulta- 

 neously with that of most of the other thrushes, except the 

 Robin. 



As to their distribution throughout the State during migra- 

 tion, there seems to be great uniformity where the conditions 

 for its food are present. Lists for May are sent me annually 

 from nearly every characteristic section of the survey, and a 

 good number for the entire summer. They wander to consider- 

 able distance from the forests for food, but only in the thickety, 

 brushland localities. 



29 z 



