PERCHING BIRDS. 207 



years that I have paid some attention to ornithology 

 in this district without being able to exhaust the 

 subject : new occurrences still arise as long as any 

 inquiries are kept alive." 



There are four British species of swallows. The 

 SAND MARTIN, a small brownish bird, by far the 

 least of any of our swallows, comes first, and may 

 be seen early in April hurrying over the surface 

 of large sheets of water or rivers, near which are 

 banks of sandy soil, in which these birds burrow 

 and build their nests. * A colony of sand-martins 

 in considerable numbers, especially when they are 

 forming a settlement, presents a very busy scene. 

 They dig away with great assiduity, using their 

 bills as pickaxes, and shovelling out the sand 

 with their feet, making so deep a burrow that it 

 is not easy to reach the nest ; the entrance, too, is 

 so small, that no bird of prey can gain access, and 

 the steep is, generally, so great, that the small 

 animals which suck eggs are not able to climb it. 

 These birds are no songsters, only making a little 

 harsh noise when any person approaches their 

 nests. 



* It is remarkable that after some years the old holes are 

 left and new ones bored. Perhaps because they become 

 foul from long use, or they may so abound with fleas as to 

 be untenable. This species of swallow is strangely annoyed 

 with fleas. 



