HOUSE-MARTINS. 167 



the same neat precaution is made use of; particularly among 

 dogs and cats, where the dams lick away what proceeds from 

 their young. But, in birds, there seems to be a particular 

 provision, that the dung of nestlings is enveloped in a tough 

 kind of jelly, and, therefore, is the easier conveyed off, with- 

 out soiling or daubing.* Yet, as Nature is cleanly in all her 

 ways, the young perform this office for themselves in a little 

 time, by thrusting their tails out at the aperture of then 1 

 nest. As the young of small birds presently arrive at their 

 f]\iKia, or full growth, they soon become impatient of con- 

 finement, and sit all day with their heads out at the orifice, 

 where the dams, by clinging to the nest, supply them with 

 food from morning to night. For a time, the young are fed 

 on the wing by their parents : but the feat is done by so 

 quick and almost imperceptible a sleight, that a person must 

 have attended very exactly to their motions, before he would 

 be able to perceive it. As soon as the young are able to 

 shift for themselves, the dams immediately turn their 

 thoughts to the business of a second brood ; while the first 

 flight, shaken off 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 

 congregations 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 altogether ; but the 

 more forward birds get abroad some days before the rest. 

 These, approaching the eaves of buildings, and playing about 

 before them, make people think that several old ones attend 

 one nest.f They are often capricious in fixing on a nesting- 



* The dung is enclosed in a thin membrane and this enables the parent 

 birds to convey it away more easily in their mouths. This is done both for 

 cleanliness and protection, for if the exuviae of the young birds accumulated 

 around the nest, it would be more readily discovered. I have watched a black- 

 bird when in removing the excrement, the membrane has burst in his mouth, 

 and have seen him shake his head, and show evident symptoms of annoyance. 

 It is generally suffered to drop during the flight of the parent bird from the 

 nest. ED. 



"I* I have seen the whole roof of the tennis court at Hampton Court covered 

 in the autumn with young martins. After playing about for some days, they 

 congregate on the aits of the river Thames. ED. 



