222 NATURAL HISTORY OF SELBORNE. 
ely hE Ro Oa Ka Xe 
TO THE SAME. 
SELBORNE, May 13th, 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 
dvriotopyi), 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. 
