CHAPTER V. 
THE VOICE OF BIRDS.* 
Aste from the pleasure to be derived from the calls 
and songs of birds, their notes are of interest to us as 
their medium of expression. No one who has closely 
studied birds will doubt that they have a language, limited 
though its vocabulary may be. 
Song. —Song is a secondary sexual character, generally? 
restricted to the male. With it he woos his mate and 
gives voice to the joyousness of nesting time. In some 
instances vocal music may be replaced. by instrumental, 
as in the case of the drumming wing-beat of the Grouse, 
or the bill-tattoo of the Woodpeckers, both of which are 
analogous to song. 
The season of song corresponds more or less closely 
with the mating season, though some species begin to 
sing long before their courting days are near. Others 
may sing to some extent throughout the year, but the 
real song period is in the spring. ; 
Many birds have a second song period immediately 
after the completion of their postbreeling molt, but it 
usually lasts only for a few days, and is in no sense com- 
parable to the true season of song. This is heralded by 
the Song Sparrow, whose sweet chant, late in February, 
*See Witchell. The Evolution of Bird Song (Macmillan Co.), 
Bicknell, A Stndy of the Singing of Our Birds; The Auk (New York 
city), vol. i, 1884, pp. 60-71, 126-140, 209-218, 822-832; vol. ii, 1885, 
pp. 144-154, 249-262. 
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