The Chimney Swift 221 



gradually softens and then it not infrequently happens 

 that the nest, weighed down by the young birds, falls 

 to the bottom of the chimney. If the fall does not 

 kill the nestlings, they usually climb up the sides of 

 the chimney for a short distance, and here they 

 remain in a hanging position, being fed by the old 

 birds until they are ready to fly and shift for them- 

 selves. 



The young swifts are very interesting, although 

 somewhat uncanny in their actions, resembling in 

 their constant movements a bunch of wriggling snakes. 

 At first I thought they were irritated by the vermin, 

 so common about birds' nests, but as I failed to find 

 anything of the sort, I looked for another cause. 

 After careful observation I concluded that the move- 

 ments were due to an innate desire on the part of 

 the young birds to preen their feathers, although the 

 feathers had scarcely started. One does not become 

 thoroughly aware of the constant motion of the young 

 birds until one attempts to "take their picture," 

 when their restlessness becomes painfully apparent; 

 it being almost impossible to catch the whole brood 

 motionless, even for the fraction of a second. For 

 this reason, in addition to the fact that their surround- 

 ings are such that the light is poor at the best, .they 

 are most difficult young birds to photograph. 



