210 THE SWIFTS. 



wild geese were heard passing St Andrews before the swallows 

 had left. 



Sand-martins prefer sequestered spots, like the banks of 

 rivers or braes. The nests are near the surface of high cliffs, 

 or where there is a stratum of sand, or within 4 feet of the 

 ground in low river banks. They have two broods in the year, 

 and for a time feed their young on the wing. Sometimes their 

 nests are invaded by sparrows. When two quarrymen were 

 working below they heard the martins skirring above them. 

 A young one fell at their feet. On looking up they saw a cock 

 sparrow holding another one by the throat, which he also 

 trundled over. He did the same to the other three, and took 

 possession of the nest. The old ones got ten of their friends, 

 and tried nearly all day to dislodge the daring burglar, but he 

 beat them all off. The quarrymen were so angry at the little 

 thief that they got a long pole and a piece of clay and shut him 

 up to perish in his stolen abode. 



Genus, Cypselus. 



Swift, Generic Characters. 



The features are — bill very short, triangular, and wide at the 

 base, the gape extending beyond the eye, Nature's design 

 being to enable them to catch flies readily. The nostrils are on 

 each side of the ridge (unlike the swallow's, which are at the 

 base). They are long and open, having a margin of small 

 feathers. The tarsi are very short and thick, and covered with 

 short hair; the feet have four toes, all pointing forward — 

 unlike all other biids, which have three before and one behind, 

 each entirely separate, and armed with strong hooked claws 

 (more like a quadruped's than a bird's), which enables them to 

 cling to a perpendicular surface — a wise provision, as their 

 nests are generally in holes of old buildings or perpendicular 

 cliffs. Owing to their extreme shortness of legs and length of 

 wings they cannot fly from a flat surface, so they never alight 

 on the ground, and only on such places as have a brink, from 

 which they can fly in a curve. They cannot walk unless with 

 a hobbling gait ; and also, unlike other birds, their toes have only 

 two joints — the smallest toe, which should be the hind one, 



