270 THE BIRD WATCHER 
to me to bear upongghe foregoing remarks.’ Here 
a stone-curlew that had been sitting quietly for some 
time rose and uttered some shrill cries, in obedience 
to which another came running up, and after the two, 
standing close together, had each assumed a remark- 
able and precisely similar posture, the nuptial rite was 
performed. Were it not that, even by the witnessing 
of this last, it is not always possible to differentiate 
the sexes of birds, I could say with certainty that it 
was the female stone-curlew, in this instance, that 
called up the male; but the very striking attitude 
which the birds assumed, and which, if it was not 
a sexual display, it is difficult to know what to call it, 
was identical in both. Again, in the case of a pair of 
crested grebes that I watched during two successive 
springs everything (and there was once something 
very striking) in the nature of an antic or display 
was indulged in equally by the male and female. 
Peewits, also, behave during the nuptial season in 
a very marked manner, both whilst flying and upon 
the ground, and as far as I can make out—though 
I will not here speak with certainty—the conduct of 
both sexes is the same throughout. 
The nuptial cries or notes of birds are a chief way 
in which the one sex, on the theory of sexual selec- 
tion, endeavours to render itself pleasing to the other. 
When these charm our own ears to an extent which 
we think deserving of the name of song, it is usually 
the male alone that utters them, those uttered by the 
1 Bird Watching, pp. 18-19. 
