1 64 NATURE'S STORY OF THE YEAR 



minutes together ; and their return is first an- 

 nounced by the loud outcry, " Swee ree, svvee ree 

 ree." 



At from thirty-five to forty minutes after sunset 

 the noisy cluster of swifts flies at a considerable 



SWIFTS GOING UP FOR THE NIGHT. 



height above the houses, and often rises much 

 higher, only to descend again. But soon they 

 begin to make upward rushes which bring them 

 to successively higher levels ; and they do not 

 return. They are now keeping fairly close 



