THE VIREO AND THE COWBIRD 133 



problems must often prove on investigation to be the 

 most difficult of solution. How often do we settle 

 questions offhand and to our entire satisfaction, only 

 to discover later on that our theories are utterly 

 groundless and ridiculous ? We have only our 

 own experience on which to work, and so we 

 endeavour to reason only from one point of view, 

 forgetting too frequently that other creatures 

 living under totally different conditions must base 

 their actions on equally different premises. 



When the vireos returned I was attracted by 

 the noise they made, and, visiting the nest, dis- 

 covered the cause of the disturbance. Such excite- 

 ment there was, chattering and commotion. Now 

 and then plaintive notes could be heard, as though 

 they were bewailing their misfortune. Many other 

 birds joined with them in their lamentations. The 

 wood-thrush, whose nest was in the near-by maple, 

 repeatedly uttered her loud single note of distress, 

 as though in sympathy with the poor little vireos. 

 But wherefore all this uproar ? Why not cast out 

 the spurious egg, destroy it, for, after all, had it any 

 right to be there ? Once more, who shall say ? To 

 us it would certainly seem far easier to throw it 

 out. But, strange to say, that is seldom, if ever, 

 done. Anything but that. Even let it hatch and 

 allow the sturdy parasite to devour by far the 

 greater share of the food brought by the industrious 

 owners of the nest, so that the rightful occupants 

 shall go hungry — yes, and even starve — for that 

 often happens. But these vireos had no intention 

 of letting the big, dull-coloured egg hatch. Soon 

 the excitement died away and they fell to work 



