172 NATURAL HISTORY 



plaintive and a jarring noise ; and also a 

 snapping or cracking, pursuing people 

 along the hedges as they walk : these last 

 sounds seem intended for menace and 

 defiance. 



The grasshopper-lark chirps all night in 

 the height of Summer. 



Swans turn white the second year, and 

 breed the third. 



Weasels prey on moles, as appears by 

 their being sometimes caught in mole- 

 traps. 



Sparrow-hawks sometimes breed in old 

 crows' nests, and the kestril in churches 

 and ruins. 



There are supposed to be two sorts of 

 eels in the island of Eli/, The threads some- 

 times discovered in eels are perhaps their 

 young : the generation of eels is very dark 

 and mysterious. 



Hen-harriers breed on the ground, and 

 seem never to settle on trees. 



When redstarts shake their tails they 

 move them horizontally, as dogs do when 

 they fawn : the tail of the wagtail, when in 



