AMERICAN ORNITHOLOGY. 



247 



Big hairy woodpeckers, high holes and even bronze grackles, were 

 driven off with a vigor which conld hardly have been expected from so 

 gentle a bird. Later, when housekeeping operations commenced, he 

 found that the nest contained four pretty blue eggs; but visiting the 

 nest again about a week later, he found only one bluebird's egg, and 

 that so pricked that it would not hatch, and accompanying it, three 

 healthy cowbird's eggs which the mother bluebird was carefully 

 guarding. The cowbird in each case must have either driven the 

 mother bird off the nest or have taken advantage of her feeding time 

 to deposit the eggs. But even so, the previous conduct of the blue- 

 birds left no room to doubt that they were perfectly capable of guard- 

 ing their nest against the intruder if they so desired. 



That the smaller birds are perfectly aware of the obnoxious nature 

 of the cowbird's egg is proved by their trouble on some occasions to 

 rid themselves of it. Why then do they tolerate the cowbird at all? 

 Is the explanation found in the fact that the covvbirds go in flocks and 

 hence overawe opposition? Or do they render some service in the bird 

 world, as for example sounding the first alarm in the presence of dan- 

 ger? Or is it possible that they take advantage of the night time to 

 lay their eggs? Or have they in themselves the power of inspiring fear 

 and terror which disarms opposition? What purpose does their exist- 

 ence serve? Who knows? 



