H2 BIRDS OF THE PLAINS 



a human being could possibly mistake for that of a crow, 

 yet our friend Corvus is unable to detect the strange egg 

 when deposited in the nest and sits upon it. It is not that 

 birds are colour-blind. The koel is able to distinguish 

 its own egg from that of the crow, for, after it has 

 deposited its egg, it frequently returns to the nest and 

 removes one or more of the crow's eggs ! I am con- 

 vinced that ordinarily a crow would have no difficulty in 

 distinguishing between the two kinds of egg ; but at the 

 nesting time it throws most of its intelligence to the 

 winds and becomes a puppet in the hands of its in- 

 stincts, which are to sit upon everything in the nest. 



I have myself placed koel's eggs in crows' nests, and 

 in every case the crow has incubated the eggs. On one 

 occasion I came upon a crow's nest containing only two 

 koel's eggs. As the nest was some way from my bunga- 

 low and in an exposed situation, I knew that, the 

 moment I left, it would be robbed by some mischievous 

 native boy, so I took the eggs and placed them in a 

 crow's nest in my compound. This already contained 

 three crow's eggs, two of which I moved, substituting 

 the koel's eggs for them. The crow's eggs had only 

 been laid three or four days, but the koel's eggs were 

 nearly incubated, since both yielded chicks on the third 

 day after I placed them in the nest. If nesting crows 

 think, that pair must have been somewhat surprised at 

 the speedy appearance of the chicks ! 



In all, I have placed six koel's eggs in four different 

 crow's nests, and as I have already said, in no single 

 instance did the trick appear to be detected. In the 

 majority of cases, I did not trouble to keep the number 



