156 
INTRODUCTION. 
which indicates this display, so common that it 
has given rise to it. It is produced, however, in 
a different manner from the raising or displaying of 
the plumes, which in fact are too short to admit of 
their being exhibited or raised as ruffs or lengthened 
tail-coverts ; but they have the power of changing 
the position of the feathers by a muscular action, so 
as to throw their brilliant reflective powers into 
view of the spectator, or to exhibit parts which 
were otherwise concealed ; and he likens or compares 
this powor to that possessed by some of the African 
antelopes, which at will suddenly display concealed 
white portions of the hair, which in that state forms 
conspicuous pale markings. It is during this season 
of incubation also, that any variation of notes is 
principally shown, as among the Humming-birds, 
the call when in search of food, or when irritated, 
is sharp, and indicates anxiety or a restless desire to 
obtain the object ; hut, unlike them, they possess 
at times an agreeable note or warble, having con- 
siderable melody. Vaillant states this of several 
species, and in the Voyage of Frecynet, indica- 
tions of them being sometimes nocturnal occur, 
“ At night they have a lengthened song, the mo- 
dulations of which are very agreeable."* Latham 
adds to his description of the Blue-rumped Creeper, 
— “ Said to sing as well as any Nightingale, with 
a sweeter voice.” t The Diceum hirundinaceum 
sings in “ a very animated and long-continued strain, 
Frecynet, p. 26. 
f Gen. Hist., ix. p. 23S. 
