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 faune (such as the Allegha- 
nian and Canadian), 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 Conway, where (at least in one grove) the Swainson’s 
Thrushes and Black-throated Blue Warblers were apparently 
common. The dividing line, already spoken of, must necesta- 
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 Flycatchers 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 pu, which 
is often repeated, and which recalls the voice of the Great 
Crested Flycatcher. Another note is pu-ée, which is uttered 
in a peculiar tone, very distinct from that of the Wood Pewee, 
90 See §17, VI, A, (c). 
