40 - THE HOUSE SPARROW: 



numerous we have had plenty of swallows : from the 

 places they are in their nests cannot well be counted, but 

 their numbers seem to vary much from year to year. My 

 general impression is that the numbers of swallows about 

 a place are but slightly diminished by the presence of a 

 great number of martins ; and I do not see that swallows 

 increase much in numbers where the martins disappear. 

 As the two species do not displace or replace each other 

 to any great extent, it would seem, though they probably 

 eat some insects in common, that their food is mainly 

 different, and that we need both species to destroy differ- 

 ent insects. So far as I have observed, swallows as a rule 

 take larger insects than martins. From the fact that the 

 martins can maintain themselves in far greater numbers 

 about a place, it is evident that their peculiar food must 

 be much more abundant than that of the swallows."^ 



Besides those already mentioned, most common birds 

 abound in my place ; these are all more useful or harm- 

 less, or both, than sparrows, and I think that most of 

 them do better and are more numerous for the absence of 

 these. It is difficult to make out and speak positively 

 about partial displacement of other birds by sparrows. 

 So many things may affect the numbers of various birds, 

 and it is impossible to know how many of each species 

 would be at my place were it infested with sparrows, and, 

 again, how far, in the absence of sparrows, the numbers 

 of other insect-eating birds are affected by my multitude 

 of martins. I can only say what is my general impression. 

 The harmless and useful hedge-sparrow for instance 

 abounds, thriving in bad times on waste which would feed 

 his greedy namesake, were he tolerated here. No doubt 



* The insect food of these and other birds is a subject which much 

 wants investigating. 



