AN ESSAY ON BIRD-MIND 125 



when the bird is full of energy and outer conditions 

 are favourable, gives pleasure. The best-known ex- 

 ample is the song of song-birds. This, as Eliot How- 

 ard has abundantly shown, is in its origin and es- 

 sential function a symbol of possession, of a nesting 

 territory occupied by a male — to other males a no- 

 tice that "trespassers will be prosecuted," to females 

 an invitation to settle, pair, and nest. But in all 

 song-birds, practically without exception, the song is 

 by no means confined to the short period during 

 which it actually performs these functions, but is 

 continued until the young are hatched, often to be 

 taken up again when they have flown, or after the 

 moult, or even, as in the Song Thrush, on almost 

 any sunny or warm day the year round. 



And finally this leads on to what is perhaps the 

 most interesting category of birds' actions — those 

 which are not merely sometimes performed for their 

 own sake, although they possess other and utili- 

 tarian function, but actually have no other origin or 

 raison d'etre than to be performed for their own sake. 

 They represent, in fact, true play or sport among our- 

 selves; and seem better developed among birds than 

 among mammals, or at least than among mammals 

 below the monkey. True that the cat plays with the 

 mouse, and many young mammals, like kittens, 

 lambs, and kids, are full of play; but the playing with 

 the mouse is more like the singing of birds outside the 

 mating season, a transference of a normal activity to 

 the plane of play; and the play of young animals, as 



