vi On the Songs of Birds 145 



is warm and the sun shines, they will begin to sing 

 at once ; if it is cold and dreary, they will wait. 

 You may hear a Nightingale or a Blackcap singing 

 heartily but quite alone, not another bird of the 

 species within half a mile of him. Such a solitary 

 Nightingale sings in the parks at Oxford every 

 spring. This may indeed be practice ; and it further 

 serves the purpose of attracting a mate, and as a 

 rule succeeds : it may also attract other males, and 

 then there is rivalry and perhaps fighting. But 

 when the pairing is over, the singing goes on with 

 almost as much vigour as before ; and it is then used 

 to divert and please the hen during the labours of 

 nest-building and incubation, and also, no doubt, to 

 keep her aware of his being close at hand. In one 

 particular species, the Wood Warbler, it is especially 

 delightful to watch the communications which pass 

 between the male and female during the nesting 

 time. As was pointed out to me by a most exact 

 observer, the real song is then only uttered when the 

 hen bird is on the nest : when she is off, its place is 

 taken by a long-drawn call-note, far more beautiful 

 in tone than the song itself; and the hen herself 

 responds in notes similar in tone, but somewhat 

 shorter and quicker. And I have read a curious 

 statement by a good observer of the early part of this 

 century, that the male Blackcap will sing even while 

 taking his turn at sitting on the eggs, still keeping 



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