WHERE SWALLOWS ROOST 103 



to observe. 49 This habit does not appear to have 

 been previously recorded, and I am by no means 

 certain that the explanation offered is the true 

 one. 



Frequently one or more flocks, varying in size 

 from eight or ten to several hundred birds, may be 

 seen in the road, where I at first supposed they were 

 "dusting," but soon noticed that most of the birds 

 after alighting in the road were motionless. They 

 did not move about as though searching for food, 

 but occasionally the actions of a pair enabled one 

 apparently to determine the sex of each individual, 

 and more often a bird would pick up a bit of dried 

 grass and fly up into the air with it. Sometimes it 

 was carried fifty yards or more and then dropped ; 

 at others, the birds would carry it to the telegraph 

 wires above, and drop it after perching a moment. 

 Without exception, all the birds seen to alight in the 

 road were in the dull, immature plumage of birds of 

 the year, and in their actions, as Mr. William Brew- 

 ster has remarked (The Auk, 1898, p. 194), they evi- 

 dently gave a premature exhibition of the procrea- 

 tive and nest-building instincts. 61 



Additional evidence of the possession of inher- 

 ited knowledge was apparently given by many Tree 

 Swallows, who were frequently seen hovering about 

 a pile standing in the creek. 50 At first it was sup- 

 posed that these birds were feeding on insects which 

 had alighted on the pile ; but the number of birds 

 often a dozen or more seen fluttering about it, and 

 the persistency with which they remained there, 

 forced the conclusion that in a wholly unreasoning 

 way they were looking for a nesting site. 



