SWALLOWS. 



525 



slender. The metatarsus is bare, save for a tuft of feathers at its base. The 

 sand-martins are pre-eminently gregarious in the nesting-season ; the best known 

 and most widely distributed member of the genus being the European species 

 (C. riparia), which extends its range to Northern Asia and North America. The 

 Indian species (C. sinensis) is resident throughout the northern portions of the 

 Indian Empire; while Cowans' sand-martin is peculiar to the island of Madagascar; 

 several species also inhabiting Africa. The common sand-martin (C. riparia) arrives 

 in the northern parts of its breeding-range a week or two in advance of the larger 

 swallows, and may generally be seen in sheltered situations during the last days 



SAND-MARTIN AND PURPLE MARTIN (J Hat. size). 



of March, frequently hawking flies under the crags that overhang salmon-rivers. 

 It soon proceeds to the nesting-grounds, and commences to tunnel the chamber 

 intended to contain its eggs in some sandy bank, gravel-pit, or railway cutting ; 

 although sometimes it digs a hole in the bank of a small stream, or even burrows 

 in a heap of sawdust. The male sand-martin is a somewhat jealous bird, and often 

 indulges in a struggle with some rival. The eggs, which are pure white without 

 spots of any kind, are laid in a hole lined with stems of grass and feathers. When 

 the young are able to fly, they join the company of other swallows and martins, 

 and are constantly to be found by the riverside. The sand-martin leaves its 

 summer-quarters earlier than its congeners, and its movements are less extended. 

 On one occasion we fell in with thousands of these martins steadily migrating along 

 the east coast of England, the air being literally full of birds for half an hour, flock 



