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 different 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.[1]
Besides those already mentioned, most common birds abound in my place; these are all more useful or harmless, 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.
