BIRDS. 
339 
spring, it IS not easy to say how the Hirundines subsist ; for 
they withdraw themselves, and are hardly ever seen, nor do 
any insects appear for their support. That they can retire 
to rest, and sleep away these uncomfortable periods as the 
bats do, is a matter rather to be suspected than proved : or 
do they not rather spend their time in deep and sheltered 
vales near waters, where insects are more likely to be found ? 
Certain it is that hardly any individuals of this genus have 
at such times been seen for several days together. 
September 13, 1791. The congregating flocks of Hirun- 
dines on the church and tower are very beautiful and 
amusing ! When they fly off all together from the roof, on 
any alarm, they quite swarm in the air. But they soon settle 
in heaps, and preening their feathers, and lifting up their 
wings to admit the sun, seem highly to enjoy the warm 
situation. Thus they spend the heat of the day, preparing 
for their emigration, and, as it were, consulting when and 
where they are to go. The flight about the church seems 
to consist chiefly of house martins, about four hundred in 
number ; but there are other places of rendezvous about the 
village frequented at the same time. 
It is remarkable that though most of them sit on the 
battlements and roof, yet many hang or cling for some time 
by their claws against the surface of the walls, in a manner 
not practised by them at any other time of their remaining 
with us. 
The swallows seem to delight more in holding their 
assemblies on trees. 
November 3, 1789. Two swallows were seen this morn- 
ing at Newton vicarage-house, hovering and settling on the 
roofs and out-buildings. None have been observed at Sel- 
borne since October 11. It is very remarkable that after 
the Hirundines have disappeared for some weeks, a few are 
occasionally seen again, sometimes in the first week in 
November, and that only for one day. Do they not with- 
draw and slumber in some hiding-place during the interval ? 
for we cannot suppose they had migrated to warmer climes, 
and so returned again for one day. Is it not more probable 
that they are awakened from sleep, and, like the bats, are 
come forth to collect a little food? Bats appear at all 
