196 THE NATURAL HISTORY 



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 all build in the church, yet so fre- 

 quently haunt it, and play and rendezvous round it, that 

 they are easily enumerated. The number that I con- 

 stantly 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 orni- 

 thology, I have always supposed that that sudden reverse 

 of affection, that strange avria-Topyri, 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. 



