568 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



GEOTHLYPIS PHILADELPHIA, [Wils.) Bd. 



Mqurnikg Warblee. 



1 was agreeably sin'i)rised to find tins sjjecies, wliicb is rather rare in 

 most Eastern localities, breeding abundantly at Pembina ; and I suspect 

 that the Mississippi Valley, rather than the Atlantic seaboard, may be the 

 principal line of migration along which it comes liom its winter home in 

 Central America to its breeding resorts along the northern boundary of 

 the United States. At the end of June I found a nest, supposed to be 

 of this species, but the identification was not at all satisfactory. The 

 birds were breeding in June, as I knew by the different actions of the two 

 sexes. The males were in full song, and, contrary to their very secretive 

 habits during most of the year, became rather conspicuous, not only by 

 their singing, but by their custom of leaving the dense shrubbery and 

 undergrowth, in which they usually hide, to mount to the tops of the 

 trees. The females, on the other hand, were extraordinarily quiet and 

 retiring ; so much so, that during the whole month I secured not a single 

 specimen, though nearly a dozen males were taken without much diffi- 

 culty. The birds were only observed in the heavy timber of the river- 

 bottom in this locality, and were not afterward encountered during our 

 progress westward; whence I suppose this is about the limit of their 

 Western dispersion. The species appears to breed in like numbers in 

 various portions of Minnesota, where Mr. T. M. Trii)j)e has found it 

 haunting the tamarack swamps and iidjoiuing damp thickets. He cor- 

 roborates the habit I have just mentiontd of aectnding to the tree-tops; 

 and, like myself, was unfortunate in finding no nest, though he fre- 

 quently saw the old birds feeding their young in the latter part of June 

 and early in July. The song is a loud, clear, and agreeable warble, reit- 

 erated with great persistency. 



List of specimens. 



GEOTHLYPIS PHILADELPHIA MACGILLIVRAYI, {And.) Bd. 



Macgillivray's Warbler. 



A single specimen was secured in the Rocky Mountains in August. 

 In this latitude at least, the present bird does not appear to approach 



