Introduction 
11 
perfect before the arrival of the females, and that it deterior¬ 
ates immediately on their arrival; so that if it be a mating- 
song at all, it is rather a prothalamium than an epitlialaminm. 
It will be noted that Yarrell simply assumes that the singing of 
the male has secured him a mate. If the singing did so, or 
could do so, why should the song deteriorate at the very time 
it should be at its highest excellence? May it not be that the 
increased spring-vitality finds expression in song whilst the 
females are absent, and is diverted to the passion of mating 
when the females do arrive? One reason for the song being 
usually confined to the male is that the superabundant energy 
that in the male is transformed to song or to colour, in the 
female is absorbed in egg-laying and rearing. To this idea 
objection can also, of course, be urged by pointing out 
exceptions. 
Further, if the precession of the males be a sexual instinct, 
e taken solely in order that the song may be 
practised without the distraction caused by the presence of 
females, since the males of most migratory birds, whether 
singers or not, appear before the females (DD, p. 212). So 
that the fact that the blackcap, nightingale, and other warblers 
practise their song before the arrival of the females would 
appear to be as much incidental as significant. Swallows 
usually arrive in pairs (WW, p. 59). 
Is the song to be considered sexual when both sexes sing, as 
do the tui and be]l-bird? I have detected no difference in the 
songs of the male and female tui. The song of the male bell- 
bird is quite different from that of the female, but the song 
of the latter is heard far more frequently; I have heard the 
song hundreds of times, but have heard the song of the male 
only twice. 
Is there is a single recorded instance (except, perhaps, 
amongst caged birds) of a female having shown that the song 
of the male attracted her? I have never seen a single instance, 
nor have I ever heard of one. Twice I have seen a male blight- 
bird start his song, the female immediately flying to the 
attack, compelling him to desist. I have seen a tui sidling 
