VII Aristotle on Birds 199 



selves. Conservative as animals are, and especially 

 birds, they do undoubtedly possess the power of 

 modifying their habits to suit themselves to altered 

 conditions of life ; and every faithful record of those 

 habits at one particular point of time may at some 

 remote date become a landmark in the slow progress 

 of a species. 



As I write this paper there are but a few yards 

 from me, under the eaves of the house, several nests 

 of that familiar bird the House-martin, which we 

 have come to associate so closely with the dwellings 

 of man. How long, we may ask, has it had this 

 habit of building on human habitations ? There are 

 still places, even in England, where it nests under 

 the ledges of cliffs ; and we may be certain that this 

 was its original habit. Can we learn anything from 

 Aristotle as to the time at which it first began to 

 take advantage of the architectural skill of man ? 



I cannot find any passage in his book that betrays 

 a knowledge of this bird. He certainly knew the 

 Swallow, and describes very accurately its manner 

 of building with mud and straw ; he also knew the 

 Swift, and possibly too the Sand-martin or the Crag- 

 swallow, or both ; but he has not a word to say of a 

 bird of this kind which has a conspicuous white 

 patch just above the tail. If the House-martin had 

 been known to him at all, I cannot believe that he 

 would have confused it with others of its kind; and if 



