THE NATURAL HISTORY OF SELBORNE. ; 89 
The grasshopper-lark chirps all night in the height of sum- 
mer. 
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 
Ely. The threads sometimes discovered in eels are perhaps 
their young: the generation of eels is very dark and myste- 
rious. 
Hen-harriers breed on the ground, and seem never to settle 
on trees. 
[Of this handsome bird White has the following notes in his 
Observations on Nature: —“ A neighboring gentleman sprung 
' a pheasant in a wheat stubble, and shot at it; when, notwith- 
standing the report of the gun, it was immediately pursued by 
the blue hawk, known by the name of a hen-harrier, but 
escaped into some covert. He then sprung a second, and a 
third, in the same field, that got away in the same manner; 
the hawk hovering round him all the while that he was beating 
the field, conscious no doubt of the game that lurked in the 
stubble. Hence we may conclude that this bird of prey was 
rendered very daring and bold by hunger, and that hawks 
cannot always seize their game when they please. We may 
farther observe, that they cannot pounce their quarry on the 
ground where it might be able to make a stout resistance, 
since so large a fowl as a pheasant could not but be visible to 
the piercing eye of a hawk, when hovering over the field. 
Hence that propensity of cowering and squatting till they are 
almost trod on, which no doubt was intended as a mode of 
security, though long rendered destructive to the whole race of 
gallinze by the invention of nets and guns.”’ | 
When redstarts shake their tails they move them horizon- 
