[ 44 ° ] 
♦ 
mer Abode in defolate fenny Parts of our Ifland. 
When the Severity of our Winters deprives them of 
their liquid Suftenance, Necefiity obliges them to re- 
tire towards the Sea in numerous Flights, where in 
open brackiflh Waters they find Relief, and at the 
Approach of the Spring they retire to their Summer 
Receffes. But thefe cannot be included among thofe 
ufually termed Birds of Paffage. 
Befides the different Kinds of Swallows, I know 
of but one Kind of European Bird that fubfifts in like 
manner by catching its Food on the Wing, and that 
is the Caprimulgus or Goat fucker, the capacious 
Stru&ure of whofe Mouth and Gullet is formed to 
receive Infeds'of the larger Kinds, as Scaraba 't y Grille - 
talp<e, &c. Thefe are alfo Birds of Paffage. 
We have, ’tis hoped, made it pretty evident, that 
Summer Birds of Paffage come to and depart from 
us at certain Seafons of the Year merely for the fake 
of a more agreeable Degree of Warmth, and a 
greater Plenty of Food 5 both which Advantages they 
procure by an alternate Change of Climate ; but the 
Migration of Winter Birds of Paffage, and particu- 
larly of Fieldfares and Redwings, is much more dif- 
ficult to be accounted for, there being no fuch ap- 
parent Neceility, either on the Score of Food or 
Climate, for their Departure from us. 
The Reafon of their coming here in Winter is, 
Vis highly probable, for the fake of Food, and a 
more fuitable Climate than that they leave behind 
them ; but, in fome fevere cold Seafons, and when 
there is a Scarcity of Berries they fubfift here with 
Difficulty, and are evenfamifhed fometimes for Want 
of fufficient Food 5 yet what appears mpft unac- 
countable 
