222 NATURAL HISTORY OF SELBORNE. 



LETTER XXXIX. 



TO THE SAME. 



SELBORNE, May i^th, 1778. 



DEAR SIR, Among the many singularities attending those 

 amusing birds the swifts, I am now confirmed in the opinion that 

 we have every year the same number of pairs invariably ; at least 

 the result of my inquiry has been exactly the same for a long time 

 past. The swallows and martins are so numerous, and so widely 

 distributed over the village, that it is hardly possible to recount 

 them ; while the swifts, though they do not build in the church, yet 

 so frequently haunt it, and play and rendezvous round it, that they 

 are easily enumerated. The number that I constantly find are 

 eight pairs ; about half of which reside in the church, and the rest 

 build in some of the lowest and meanest thatched cottages. Now 

 as these eight pairs, allowance being made for accidents, breed 

 yearly eight pairs more, what becomes annually of this increase ; 

 and what determines every spring which pairs shall visit us, and 

 reoccupy their ancient haunts ? 



Ever since I have attended to the subject of ornithology, I have 

 always supposed that that sudden reverse of affection, that strange 

 ai/rioropy?;, which immediately succeeds in the feathered kind to the 

 most passionate fondness, is the occasion of an equal dispersion of 

 birds over the face of the earth. Without this provision one 

 favourite district would be crowded with inhabitants, while others 

 would be destitute and forsaken. But the parent birds seem to 

 maintain a jealous superiority, and to oblige the young to seek for 

 new abodes ; and the rivalry of the males in many kinds, prevents 

 their crowding the one on the other. Whether the swallows and 

 house-martins return in the same exact number annually is not easy 

 to say, for reasons given above ; but it is apparent, as I have 

 remarked before in my Monographies, that the numbers returning 

 bear no manner of proportion to the numbers retiring. 



