292 Observations on the 
in obtaining it, will be more than compensated 
by the numerous advantages it affords. In 
many instanc:s it enables him to detect spe- 
cies that might otherwise elude his observa- 
tion. Thus, the land rail, concealed in the 
long grass of luxuriant meadows, where it 
runs with great rapidity, and is sprung with 
difficulty ; the grasshopper warbler, closely 
embowered in thick hedges and bushy dingles, 
where it employs every artifice to escape no- 
tice; and the sedge warbler, secluded amid 
the reeds and other aquatic productions of 
pools and marshes ;—are much more frequent- 
ly heard than seen: the harsh call of the first, 
the sibilous note of the second, and. the hur- 
ried song of the last, being repeated through 
the night, in fine weather, during the breed- 
ing season, 
It also enables him to identify species with 
the utmost precision: in some cases, indeed, 
with much greater certainty than he could 
by the minutest examination of good speci- 
mens. The three species of willow wren, 
_for example, so strongly resemble each other, 
that even nice observers might have some 
difficulty in determining them by inspection ; 
and, accordingly, we find that they have 
been the source of much confusion, perplex- 
_ity, and error, among writers on ornithology: 
