THE SWALLOW TRIBE. 341 



Proofs to tlie contrary have been obtained, not 

 only by the testimony of those who have seen 

 them while crossing the ocean, but by various 

 experiments made upon the birds. Some of these, 

 especially those made by Spallanzani, are so cruel, 

 that we feel that knowledge has been purchased at 

 too great a price. The 10th of April seems to 

 be established as the average time of their return 

 to our island, but this may be rather earlier 

 or later in the season, according to the weather. 

 As Mr. Broderip has observed, " the songsters 

 which visit us in the season of love, hope, and joy, 

 have very retentive memories," for the same pair 

 of birds will return to their old homes. A silken 

 thread attached to the leg of a swallow in the 

 spring, has served to prove that year after year 

 the birds sought their earliest dwelling, and pro- 

 bably came back to it all their lives. So fond are 

 they even of their old neighbourhood, that if the 

 nest is destroyed, they will build again in the 

 very spot. 



The swallow seems to prefer the dwellings of 

 man as the place in which to build its nest, and 

 often selects such as are near water. In such 

 places, insects are most numerous; and here, 



