Birds of Britain 



Chinese. With our species, however, the amount of saliva 

 used is comparatively small; it does not often collect 

 material for its nest, but makes use of the accumulation of 

 rubbish usually found under roofs, and, hollowing out a 

 shallow depression, cements it into a permanent cup. Two 

 or three dull, oblong, white eggs form the clutch. The 

 young when first hatched are naked ; they stay in the nest 

 a long time, not leaving it until fully fledged. When, 

 however, they leave their home and drop into the air for 

 the first time, they fly off at once and appear as much at 

 home on the wing as their parents. For a few days they 

 return to the nest to rest, and then a week or two after 

 they are fledged, about the beginning of August, they leave 

 us for their tropical winter home. These birds occasionally 

 perform curious aerial evolutions on warm summer nights. 

 As darkness comes on they become very restless, screaming 

 round the tower or belfry as they dash by in wide circles ; 

 gradually they rise higher and higher in the air till they 

 become mere specks, and are finally lost in the darkness. 



Here again our ignorance comes in and our story must 

 end. Observers have sat up in vain till two or three in 

 the morning, awaiting their return. Not one has reappeared, 

 and yet the next day they will all be seen back again, 

 apparently unwearied by their restless night, but rather 

 enjoying to the full the marvellous powers of flight which 

 they have inherited. 



The sexes and young are alike in plumage and are of 

 a uniformly dark sooty brown, the chin and throat being 

 dull white. The tail is short and slightly forked; wings 

 very long and narrow. The feet are extremely feeble, the 



