DELAWARE VALLEY ORNITHOLOGICAL CLDB. 21 



hard to approach, and as the song was new, both to Mr. Brown 

 and myself, we were at first in some doubt as to the identity of 

 the bird. On the afternoon of June 23, however, while in the 

 depths of the swamp, among a dense tangle of rhododendrons 

 and spruces, one of these birds unconsciously lit almost by my 

 side and immediately began singing. Of course I had an ad- 

 mirable chance to observe it, and at once felt no doubt about its 

 being an Olive-backed Thrush. Later, we had a fine chance to 

 hear both this species and the Wilson's near Oleona, and the 

 difi'erence between the two songs was very striking. 



75. Hylockhla aonalaschkas pallasii. Hermit Thrush. — For 

 some unknown reason this bird was neither seen nor heard 

 during our entire trip. Why it should have been absent where 

 both the Olive-back and the Wilson's were common, certainly 

 seems strange. Yet in this connection it may be of interest to 

 state that the Hermit Thrush was absent this summer (1900) 

 in Susquehanna Co. from localities where I have never failed to 

 find at least three or four pairs breeding in previous years. In 

 fact, during the whole of June and July I heard but one Hermit 

 Thrush near Dimock. Has any one else noted the scarcitj'' of 

 this bird during the past breeding season, and if so how can it 

 be accounted for? Is it not possible that it, like other repre- 

 sentatives of the Canadian fauna, is being slowly driven away 

 by those very changes in environment caused by the ravages of 

 axe and fire, which in turn are attracting such southern types 

 as the Chat? 



76. Merula migrator ia. Robin. — Found about cleared ground. 



