156 THE PLAY OF ANIMALS. 



them.* The weaver bird offers the most familiar exam- 

 ple. Cams, too, speaks of the plaiting "which many 

 birds work at if prevented from building nests for them- 

 selves. It is especially interesting to watch the Ploceus 

 sanguinirostris, now so common in Europe, when it can 

 not build its peculiar purse-shaped nest, how it makes 

 use of every available scrap of thread or straw in inter- 

 weaving and adorning the bars of its cage. Surely this 

 bird evinces a certain intelligence, which is not of the 

 lowest order, as any one must be convinced who watches 

 it at work for any length of time — how it holds a 

 thread in its claw, seizes it with the beak, pushes it 

 through the grating, ties a good knot, and proceeds to 

 weave it in and out." f 



This might be regarded as a kind of play, depending, 

 however, upon the abnormal conditions of the bird's life. 

 But for its artificial milieu it would build a nest, and 

 since instinct forces it to build something, its activity 

 assumes a playful character, owing to circumstances im- 

 posed by man. The attempts of some male birds to build 

 nests on their own account, before they have assumed 

 the responsibility of wedlock, may, however, be regarded 

 as purely playful. The Miillers tell us that the wren 

 does this, sometimes making two or three nests imper- 

 fectly alone, before he unites with the female in build- 

 ing the one on which she sits. " This haste to build," 

 says the observer, "is nothing but happy sportiveness 

 on the part of the little creature bewitched by love." 

 It is probably due to the fact that the awakening of sex- 

 ual passion arouses all the instincts connected with it 

 to activity. Many birds pick on the ground during their 



* Descent of Man, ii, p. 52 f. 



t C G. Cams, Vergleichende Psychologie, 1866, p. 213. 



