OF NEW ENGLAND. 285 



swampy fields. Unlike many other flycatchers, they are some- 

 what shy of man's approach. They usually remain within fif- 

 teen feet of the ground, but they sometimes take both higher 

 and longer flights than I have ever known the Least Fly- 

 catchers to take. ' They are in fact much less stationary than 

 most of their relations, though their general habits are the 

 same. They live much on the edges of the woods, and often 

 occur along the roadsides, where, from the tops of the bushes 

 and lower trees, they utter their peculiar notes. I have been 

 led, partly from observations on this species, to believe that 

 probably the line, separating two faunae (such as the Allegha- 

 nian and Canadian 90 ), can never be precisely defined, since 

 birds of the same district vary considerably in their latitudinal 

 range. This is even the case in more or less restricted lo- 

 calities. While walking southward through the Crawford 

 Notch, I saw or heard Traill's Flycatchers from the Willey 

 House to a point several miles nearer Conway, and beyond this 

 point the Least Flycatchers (who are comparatively rare in the 

 Canadian district) were soon heard. No more of the former 

 were seen, but the latter were frequently observable down to 

 North Conwa3 r , where (at least in one grove) the Swaiuson's 

 Thrushes and Black-throated Blue Warblers were apparently 

 common. The dividing line, already spoken of, must necestsa- 

 rily be irregular, because affected by altitude as well as lati- 

 tude. Among the White Mountains, one often finds it quite 

 sharply defined by the general face of nature and by the 

 atmosphere. 



The Traill's Ftycatchers do not, so far as I know, occur near 

 Boston in the autumn, and it is probable that they return to 

 the South by an inland route, as is the case with many other 

 birds. 



(d). Their ordinary note is a slightly querulous pit, which 

 is often repeated, and which recalls the voice of the Great 

 Crested Flycatcher. Another note is pu-ee, which is uttered 

 in a peculiar tone, very distinct from that of the Wood Pewee, 



o See 17, VI, A, (c). 



