436 The Natural History of Selborne 



asserted that these birds migrate back again from some distant 

 tropical region merely on the appearance of a fine day or two 

 at this late season of the year. Again, very early in the spring, 

 and sometimes immediately after very cold severe weather, on 

 its growing a little warmer, a few of these birds suddenly make 

 their appearance, long before the generality of them are seen. 

 These appearances certainly favour the opinion of their passing 

 the winter in a torpid state, but do not absolutely prove the 

 fact for who ever saw them reviving of their own accord from 

 their torpid state, without being first brought to the fire, and 

 as it were forced into life again ? soon after which revivification 

 they constantly die. MARKWICK. 



SWALLOWS, CONGREGATING AND 

 DISAPPEARANCE OF. 



DURING the severe winds that often prevail late in the spring 

 it is not easy to say how the hirundines subsist; for they with- 

 draw 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 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 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 400 in number ; but there are other places of 

 rendezvous about the village frequented at the same time. 



