158 
NATURAL HISTORY 
delicate texture; so nicely adapted to its peculiar pur- 
pose! This challenges, even credulity itself, and is well 
calculated to enforce the pious conclusion— that the 
Creator hath done all things well. 
Some birds associate together on particular occasions, 
or at particular seasons: others are constantly in flock, 
whether for the purpose of breeding or feeding. It is 
observed of the swallow, that, in the season of breeding, 
they will unite together for common defence. When 
they spy a hawk, or other bird of prey, they set up a pe- 
culiar kind of twittering; immediately, a number are ob- 
served to assemble together, and, when their force is suf- 
ficiently augmented, they instantly pursue and attack the 
common enemy, and drive him «quite out of their dis- 
trict. After the season of breeding, and training up 
their little families, has transpired, the swallows are ob- 
served to assemble together in great numbers; this takes 
place early in the morning, and for several mornings in 
succession: this happens about the latter end of August, 
or beginning of September. At this time, they make a 
more than ordinary chattering; mount higher in the air, 
and make greater excursions than usual— soon after this, 
they take their departure. But, their mode of migrating 
is different from that of almost all the feathered tribe. 
They do not assemble in a body, for the purpose, and 
take their departure in large flocks, as practised by the 
pigeon, black bird, &c.— but they all at once become si- 
lent, and depart singly. The time of their flight, is 
about an hour or two before sunset. At this time, they 
deviate from their usual manner of flying, in circular 
evolutions in the air, and continue on, in a direct course 
towards the south west; making daily approximations to 
the south, until they arrive at the districts, where they 
make their winter quarters. A strange report has pre- 
vailed, even among naturalists, respecting these birds; 
which is the more strange, because it is unprecedented, 
being totally unsupported by analogy or fact. It repre- 
sents these birds as passing the winter in a torpid state; 
descending to the bottoms of rivers, and sinking deep in 
mud, or in the earth, or hanging by clusters in old trees; 
