256 NATURAL HISTORY 
LETTER XXXV. 
Selborne, May 13, 1778. 
Dear Sir,—Amone the many singularities at. 
tending those amusing birds, the swifts, | 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 all build in the 
church, yet so frequently haunt it, and play and 
rendezvous around it, that they are easily enumer- 
ated. 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—yearly in- 
crease to eight pairs more, what becomes annu- 
ally 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 the sud. 
den reverse of affection, that strange dvtiotopy7, 
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 dis- 
trict would be crowded with inhabitants, while 
others would be destitute and forsaken. But the 
parent birds seem to maintain a jealous superiority, 
