264 
NATUTvAL HISTORY 
LETTER LII. 
TO THE SAME. 
Sei.eornEj Sept. 9, 1781. 
I HAVE juil met with a circumftance refpefting fwifts, which 
furniflies an exception to the whole tenor of my obfcrvations 
ever fince I have beftowed any attention on that fpecies of hirun- 
dines. Our fwifts, in general, withdrew this year about the firft 
day of Augi{fl, all fave one pair, which in two or three days was 
reduced to a fmgle bird. The perfeverance of this individual 
made me fufpecl that the ftrongeft of motives, that of an attach- 
to her young, could alone occafion fo late a ftay. I watched 
therefore till the twenty-fourth of Augujl, and then difcovered 
that, under the eaves of the church, Ihe attended upon two 
young, which were fledged, and now put out their white chins 
from a crevice. Thefe remained till the twenty-feventh, looking 
more alert every day, and feeming to long to be on the wing. 
After this day they were miffing at once; nor could I ever 
obferve them with their dam courfmg round the church in the 
a6l of learning to fly, as the firft broods evidently do. On the 
thirty-firft I caufed the eaves to be fearched, but we found in the 
neft only two callow, dead, ftinking fwifts, on which a fecond neft 
had been formed. This double neft was full of the black fliining 
cafes of the hippobofcce hirundinis. 
The following remarks on this unufual incident are obvious. 
The firft is, that though it may be difagreeable to fwifts to remain 
beyond 
