270 NATURAL HISTORY 



perceive it. As soon as the young are able 

 to shift for themselves, the dams imme- 

 diately turn their thoughts to the business 

 of a second brood : while the first flight, 

 shaken oft' and rejected by their nurses, 

 congregate in great flocks, and are the birds 

 that are seen clustering and hovering on 

 sunny mornings and evenings round towers 

 and steeples, and on the roofs of churches 

 and houses. These congregatings usually 

 begin to take place about the first week in 

 August; and therefore we may conclude 

 that by that time the first flight is pretty 

 well over. The young of this species do 

 not quit their abodes all together ; but the 

 more forward birds get abroad some days 

 before the rest. These, approaching the 

 eaves of buildings, and playing about be- 

 fore them, make people think that several 

 old ones attend one nest. They are often 

 capricious in fixing on a nesting-place, be- 

 ginning many edifices, and leaving them 

 unfinished ; but when once a nest is com- 

 pleted in a sheltered place, it serves for 

 several seasons. Those which breed in a 



