130 WILD LIFE AND THE CAMERA 



of its nature, so that it does come under the 

 heading of that much-abused word " instinct." But 

 at times birds are forced to resort to remarkable 

 expedien ts thattheir eggs and young may be pro- 

 tected. Then it is that we see a display of what 

 can only be termed intelligence : a careful weighing 

 of existing conditions and formulating of plans to 

 outwit enemies. One of the most common and 

 at the same time the most interesting example of 

 this is afforded by the way in which birds seek 

 to rid themselves of the burden of fostering the 

 cowbird's young. Much has been written on this 

 subject, and yet people in general do not realise 

 how clever the birds are. The accompanying set 

 of photographs made directly froin nature may help 

 the reader to appreciate the truth of the following 

 account of how a red-eyed vireo rid herself of a 

 cowbird's spurious egg. The cowbird, like the 

 European cuckoo, is parasitic in her habits, that is 

 to say, she relies on other birds to incubate her 

 eggs and watch over and feed her young. And it 

 is quite customary to condemn the poor cowbird 

 for such behaviour, no thought being given to the 

 reason why. Everything in nature has a reason, if 

 we would but stop to inquire into it, and anything 

 so far from the natural order of things as a highly 

 developed creature refusing to care for its own 

 young must, without doubt, have a very strong 

 and sufficient reason. Presumably the cowbird 

 cannot lay her eggs on consecutive days, four or 

 five days being, I believe, the interval between lay- 

 ings. Now it stands to reason that if she built her 

 own nest and laid, let us say, three or four eggs, the 



