SAND-MARTIN. 255 



beating steadily up wind, dipping constantly to the water to 

 pick up drifting insects, then turns and shoots down wind to 

 repeat the process. In a strong breeze it practically remains 

 over one small area, swerving to right or left, but neither 

 gaining nor losing headway. When the wind is light the birds 

 indulge in play, twittering in low tones, chasing and dodging 

 and at times even struggling in the air. The whole party will 

 leave the surface, rise and wheel at a considerable altitude, as 

 if testing the wind, then drop in a body to resume the food 

 chase. As evening approaches the flights become longer and 

 higher until all descend to roost in the old brown reeds or other 

 waterside vegetation. Long after the local birds have retired 

 to nest in river bank, sand or gravel pit, often at a distance 

 from water, fresh incursions of passage birds visit the pool, 

 depart for the north, and are replaced by new comers. The 

 reeds, marshes, osiers and sewage farms are seldom entirely 

 deserted, for a few non-breeding birds occupy them in June 

 and July until the first batch of young come to swell the nightly 

 gathering. The twittering song is continuous when the birds 

 are on the wing, and becomes a conversational undertone after 

 they have settled in the roost. The harsh alarm is heard when 

 a passing Kestrel, Crow or other suspected enemy calls for 

 combined action to drive it away. The food consists of small 

 insects, mostly gnats and other flies whose early stages are 

 aquatic. 



The Sand-Martin is sociable in its nesting habits ; from a 

 dozen to many hundred pairs will nest close together, according 

 to available space. The nests are at the end of tunnels of from 

 a few inches to three or four feet in length, bored in sand or 

 gravel ; if the bank allow, well out of reach. I have seen nests 

 burrowed just below the turf at the top of steep marl-clift's, and 

 others in cracks between stones in a sandy lane only three feet 

 above the roadway. Even the softer layers of new red sand- 

 stone are pecked into by the short and feeble-looking bill ; 



