12 XORTIl AMERRWX BIRDS. 



win«^, 4.20; tail, 3.10, — total, aboiit 7.50. Some six'cimens slightly exceed 

 these dinieiisious ; few, if any, fall short of them. 



In autumn the u^jper surface is somewhat different from that in spring, 

 being less grayish, and with a tinge of rich sepia or suuti-brown, this 

 becoming gradually more appreciable on the tail. 



A specimen from Costa llica is undistinguishable from typical examples 

 from the Eastern United States. 



Habits. Tins species, tii-st described in the ninth volume of the Pacific 

 Kailroad Surveys, beai-s so strong a resemblance to the Olive-backed Thrush 

 {T. swainsoui), that its value as a species has often been disputed. It was 

 first met with in Illinois. Since then numerous specimens have Ijeen ob- 

 tained from the District of Columbia, from Labr.idor, and the lower 

 Mackenzie IJiver. In the latter regions it Wiis found breeding abundantly. 

 It was also found in large numbers on the Anderson IJiver, but was rare 

 on the Yukon, as well as at Great Slave Lake, occurring there oidy as a 

 bird of passage to or from more northern breeding-grounds. 



In regard to its general habits but little is known. Dr. Coues, who 

 found it in L'lbnidor, breeding abundantly, s})eaks of meeting with a family 

 of these birds in a deep an<' thickly wooded ravine. The young were just 

 about to fly. The parents evinced the greatest anxiety for the safety of 

 their brood, endeavoring to lead him from their vicinity by fluttering from 

 bush to bush, constantly uttering a melancholy phcrgh, in low whistling 

 tone. He mentions that all he saw uttered precisely the same note, and 

 were very timid, darting into the most impenetrable thickets. 



This thrush is a regular visitant to ^lassachusetts, both in its spring and 

 in its fall migration. It arrives from alx)ut the first to the middle of ^lay, 

 and apparently remains about a week. It passes south about the first of 

 October. Occasionally it appears and is present in Massachusetts at the 

 same time with the Tnrdus svainsotii. From this species I hold it to be 

 unquestionably distinct, and in this opinion I am confirmed by the observa- 

 tions of two very careful and reliable ornithologists, Mr. William Brewster 

 of Cambridge, one of our most promising young naturalists, and Mr. George 

 O. Welch of Lynn, whose experience and observations in the field are 

 unsurpassed. They inform me that there are observable between these 

 two forms certain well-marked and constant differences, that never faD. 

 to indicate their distinctness with even greater precision than the constant 

 though less marked ditierences in their i)lumage. 



The Turdns alicia' comes a few days the earlier, and is often in full song 

 when the T. sicainsoni is silent. The song of the former is not only 

 totally different from that of the latter, but also from that of all our 

 other Wood Thrushes. It most resembles the song of T. pallasi, but 

 differe in l)eing its exact inverse, for whereas the latter begins with its 

 lowest notes and proceeds on an ascending scale, the former begins with 

 its highest, and concludes with its low^est note. The song of the T. swain- 



