146 IN SPRING. 



necessity for concealment does not occur to the 

 bird, and so its home is often invaded by the fe- 

 male cow-bird, and a single egg dropped'into the 

 structure as soon as, if not before, it is finished. 

 Sometimes this is put up with, sometimes not. I 

 have many times found nests that were two- 

 storied, the intrusive egg being, of course, in the 

 basement, and destroyed. This is one of the 

 best examples of bird wit of which I know. A 

 vast deal is taken into consideration while the 

 decision is being reached to build a floor over 

 the obnoxious egg, and so prevent its hatching. 

 There can be nothing of all this ascribed to 

 instinct, for then all such eggs would be de- 

 stroyed by this means, and the bird become ex- 

 tinct. On the other hand, it is but a very small 

 percentage that have the wit or courage to un- 

 dertake the work, which is evidence enough that, 

 of a given species of bird, the variation in intelli- 

 gence among individuals is very marked. This, 

 indeed, we see on every hand when birds are 

 building. Particularly noticeable is it when the 

 female bird stays at home and arranges the ma- 

 terial which her mate brings to her. This is 

 mere drudgery to the male bird, and too often 

 worthless bits are brought which the toiling 

 builder promptly rejects, and not always with be- 

 coming patience either. She speaks her mind in 

 unmistakable tones, and if not heeded after the 



