THE BIRD-LIFE OF LONDON 



similar to those of the preceding Swallows, but the flight 

 is not so powerful, more hesitating and fluttering. It is 

 rarely heard to sing, and its call is a harsh, twittering cry. 

 It is always interesting to remark how readily birds avail 

 themselves of any little advantage. For many years I knew 

 that the Sand Martin frequented the brickfields between 

 Wood Lane and the waste ground which the late Franco- 

 British Exhibition occupied. But these fields are done 

 away with now, and are being rapidly filled in. The 

 large sheet of water in the Stadium at the exhibition, 

 however, provided a haunt for several pairs of Sand 

 Martins, and the birds frequented this place all through 

 the Olympic Games. They nest in other brickfields to 

 the west of the exhibition site. The Sand Martin feeds 

 exclusively on insects. It is just as gregarious and social 

 as its allies, breeds in colonies, and returns year by year 

 to its old nesting-places. It also frequently rears two 

 broods in the summer, laying in May and July. Unlike 

 the House Martin, however, it makes its nest in a hole 

 in a bank, boring a tunnel into the soft gravel or clay for 

 several feet, and making a slight nest at the end of it, of 

 dry grass and straws, lined with feathers. The four or 

 five eggs are spotless white. A colony of Sand Martins 

 is very interesting. Birds may be seen flying to and 

 fro before the face of the bank or cliff in which the 

 nest-holes are bored ; others at intervals enter the tunnels, 

 or leave them to join the flitting throng outside. When 

 the young are reared the birds assemble into large flocks, 

 which appear to have certain rendezvous, water of some 

 kind, and here the scene is most animated. They are 

 preparing for departure ; each day the crowds increase, 

 and roost at night in some reed- or osier-bed. The 

 migration south begins in September, and continues into 

 October. Odd birds even occur near London during 

 November. I have seen this Martin as late as the middle 

 of that month at Richmond. 

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