SOms OF BIRDS. 
203 
seen especially in male humming-birds. Sometimes, how- 
ever, both sexes are equally ornamented, and in rare cases 
the female is more highly colored than the male; she is 
sometimes also larger, as in most birds of prey. There is 
little doubt that the bright colors of male birds render 
them more conspicuous and to be more readily chosen by 
the females as mates, for in birds, as in higher animals, the 
female may show a preference for or antipathy against cer- 
tam males. Indeed, as Darwin remarks, whenever the sexes 
of birds differ m beauty, in the power of singing, or in pro- 
ducing what he calls ^instrumental music,'Mt is almost 
invariably the male which excels the female. 
The songs of birds are doubtless in part love-notes, 
though birds also sing for pleasure. The notes of birds 
express their emotions of joy or alarm, and in some cases 
at least the calls of birds seem to convey intelligence of the 
discovery of food to their young or their mates.* They 
have an ear for music; some species, as the mocking-bird, 
will imitate the notes of other birds. The songs of birds 
can be set to music. Mr. X. Clark has published m the 
American Naturalist (vol. xiii. p. 21) the songs of a num- 
ber of our birds. The singular antics, dances, mid-air evo- 
lutions, struts, and posturings of different birds, are witli- 
out doubt the visible signs of emotions which in other birds 
find vent in vocal music. 
The nesting habits of birds are varied. Many birds, as 
* "It is necessary in a philosophical spirit to regard every sound 
made by a bird under the all-powerful influence of love or lust as a 
' song.' It seems impossible to draw any but an arbitrary line between 
the deep booming of the emeu, the harsh cry of the guillemot (which 
when proceeding from a hundred or a thousand throats strikes the 
distant ear in a confused murmur like the roar of a tumultuous crowd), 
the plaintive wail of the plover, the melodious whistle of the wid- 
geon, the 'cock's shrill clarion,' the scream of the eagle, the hoot 
of the owl, the solemn chime of the bell-bird, the whip-cracking of 
the manakin, the chaffinch's joyous burst, or the hoarse croak of the 
raven, on the one hand, and the bleating of the snipe or the drum- 
ming of the ruffed grouse on the other." (A. Newton.) 
