76 NATURAL HISTORY 
defcript in England, and what I have never been able yet to 
procure) retires or migrates very early in the fummer : it alfo 
ranges very high for it's food, feeding in a different region of the 
air ; and that is the reafon I never could procure one. Now this is 
exa(5lly the cafe with the fwifts ; for they take their food in a 
more exalted region than the other fpecies, and are very feldom 
feen hawking for flies near the ground, or over the furface of the 
water. From hence I would conclude that thefe hirundines, and 
the larger bats, are fupported by fome forts of high-flying gnats, 
fcarabs, ox phalange, that are of fliort continuance; and that the ftiort 
flay of thefe ftrangers is regulated by the defed; of their food. 
By my journal it appears that curlews clamoured on to 03ober 
the thirty-firfl ; fince which I have not feen or heard any. Swallows 
were obferved on to 'November the third. 
iBSBBi 
LETTER XXVn. 
TO THE SAME. 
DEAR SIR, Selborne, Feb. 22, 1770, 
E-HOGS abound in my gardens and fields. The manner in 
which they eat their roots of the plantain in my grafs-walks is very 
curious : with their upper mandible, which is much longer than 
their lower, they bore under the plant, and fo eat the root oif up- 
wards,, leaving the tuft of leaves untouched. In this refpeft they 
are 
