31 



AIR SCOUTS. 



Certain long-winged birds spend a large proportion of 

 their existence a-wing, dashing across the fields, swooping 

 across ponds, skimming over housetops, even sweeping the 

 clouds. These birds may very fittingly be termed "air- 

 scouts," — always on the lookout for insect enemies. They 

 are constantly on duty scouring the skies, performing 

 for mankind, in times of peace, services incomparably great- 

 er than those expected of our aeroplane scouts in time of 



Chimney Swift 



One of the most useful of these scouts is a "city dweller." 



Chimney Swifts at one time nested only in hollow trees 

 and in caves or cre,vices in cliffs. To-day for some unac- 

 countable reason they nest almost exclusively within the 

 depths of unused chimneys. We can readily understand 

 why they like to live in cities for there the little gnats and 

 flies they like so well are the most abundant, but it is not 

 so plain why any species of bird should desert the compara- 

 tively clean cavities of decayed trees for the dirty, sooty 

 interiors of brick chimneys. It seems like a retrogressive 

 ratlier than a progressive development. 



Swifts return to the northern states about the middle of 

 April each year, but they delay their nest building until 

 early May when the weather is more settled. It is quite 

 necessary that the air be dry w^hen they make their homes 

 for they are held together entirely by glue which does not 

 harden rapidly in damp weather. This glue is made by 

 the swifts from their saliva; it is very hard and almost 

 waterproof when dry. 



Their nest building is very interesting to watch but it is 

 a slow operation often keeping the two birds busy for a week 

 more. It is made of twigs varying in length from half an 

 inch to a couple inches. They must of necessity be dead 

 twigs for the birds break them from the tips of branches. 



