148 SPRING 



two very different families which have acquired in the same way 

 a similarity of appearance by dint of similar habits. But the 

 swift has outdone the swallows in the graces which we regard 

 as peculiarly swallow-like — the marvellous speed and agility of 

 flight, and tireless joy in flying. It is more swallow-like than 

 some of the swallows themselves ; for the fluttering buoyancy 

 of the sand-martin is a rather poor imitation of the true swal- 

 low's dash on the wing. Swifts and swallows will always be 

 regarded as members of the same natural group, though they 

 descend from two very different stocks. In some respects 

 swifts differ from the whole of the large family which includes 

 almost all our small birds, and come closest to the nightjar. 



Besides their great power of flight, this fascinating group 

 of birds has another special appeal to human interest in its 

 attachment to human dwellings. This voluntary domestica- 

 tion has reached its height in the case of the common 

 swallow, which now hardly ever nests in this country except 

 in or upon some edifice of men. The habit is not much less 

 marked in the case of the swift and house-martin ; and even 

 the sand-martin occasionally leaves its cliffs of sand and loam 

 to burrow in air or water pipes, and crevices in masonry. 

 The original nesting-place of both the swift and the swallow 

 and house-martin was on cliffs or in caves. Here swifts 

 collected their slight nests of a few straws or feathers com- 

 pacted with the saliva of which the eastern swifts' nests used 

 for bird's-nest soup are exclusively composed. Swallows 

 fixed their mud nests in cavities, and house-martins to more 

 exposed outer faces of the rock. So there must have grown 

 up a companionship between man and the birds in the 

 primaeval days when man lived as a hunter in caves, before 

 he was either shepherd or tiller of the soil. When at last he 

 built houses, it is possible that the swallows were partly 

 drawn by this habit of old companionship, and were not 



