12 XOJITII AilERR'AM BIRDS. 



wing, 4.20; tail, .'J.ld, — tutal, iiliout 7.50. Some sijeciinen.s sliglitly exceed 

 tliese diiiiensiuiis ; lew, if any, liill short of them. 



In iiutumn the ui)pei' surface is somewhat diflerent from that in s|)riny, 

 being loss grayish, and with a tinge of rich sepia or snulf-browu, this 

 becoming graiUially more ai)[)reciable on the tail. 



A specimen from Costa Ifica is iiudistinguishable from typical examples 

 from the Kastorn I'nited States. 



Hahits. This species, tirst described in the ninth volume of the Pacific 

 liailroad Surveys, liears so sti'ong a resend)lance to the Olive-backed Thrush 

 {T. mvaiiisoni), that its value as a species has often been disi)uted. It was 

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

 tained from the District of ("ohimbia, from Labra(h)r, and the lower 

 Mackenzie Kiver. In the latter regions it was ibund breeding abundantly. 

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

 on the Yukon, as well as at (rreat Slave Lake, occurring there only as a 

 bird of jiassage tj or from more northern breeding-grounds. 



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

 found it in Lal)rador, breeding !>l.imdantly, speaks of meeting with a family 

 of these l)irds in a deep anil thickly wooded ravine. The young were just 

 about to ily. The ])arents evinced the greatest an.xiety for the safety of 

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

 bush to bush, constantly uttering a nudancholy phci'ijk, in low whistling 

 tone. He mentions that all he saw uttered ])recisely the same note, and 

 wt re very timid, darting hito the most impenetrable thickets. 



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

 in its fall migration. It arrives from about the first to the middle of May, 

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

 October. Occasionally it a2)liears and is present in Massachusetts at the 

 same time witli the Turdioi ,siniinsoni. From this species I hold it to be 

 unipiestionably distinct, and in this o]iinion I am confirmed by the observa- 

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

 (jf Cambridge, one of our most ])romising young naturalists, and ]\Ir. George 

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

 unsuri)assed. Tiiey inform me tliat there are obse-vable between these 

 two forms certain well-marktid and constant differences, that never fai". 

 to indicate their distinctness with even gn-ater precision than the constant 

 though less marked dill'erenees in their ]iluniag(!. 



Tlie Tiirihix dliriir comes a few days tlie earlier, and is often in full song 

 when Ww, T. siniinsdiil is silent. The song of the former is not only 

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

 otlier Wood Thrushes. It most resembles the song of 'J'. imUani, but 

 dilfers in lieing its exact invei-se, for whereas the latter begins with its 

 lowest notes and ]iroceeds on an ascending scale, the former l)egins with 

 its highest, and concludes with its lowest note. The song of the T. nwaiii- 



