208 



Wild Birds 



wicker crates to the inside of chimneys. From the standpoint 

 of the Swift the change has really been very slight, and had it 

 not become so widespread it would have attracted little atten- 

 tion. This bird was probably drawn to the town and open 

 country by the greater abundance of its insect prey, and to the 





Fig. 126. Male Redwing Blackbird cleaning the nest. 



mind of the Swift a chimney cannot be very different from a 

 hollow tree. Its instinct probably does not lead it to select a 

 dead tree for its roosts or nests because it is a tree, any more 

 than it leads it to prefer a sycamore to an oak. What is prob- 

 ably inherited is the tendency to seek a dark or cavernous place 

 with easy entrance and exit. The chimney which emits no 

 smoke in summer and usually stands in the open, fulfils every 

 requirement in places where hollow trees are scarce. 



