104 NATURAL HISTORY OF SELBORNE. 
Of the sedge-bird be pleased to say it sings most part of tbe 
nigbt ; its notes are hurrying, but not unpleasing, and imitative 
of several birds ; as the sparrow, swallow, sky-lark. When it 
happens to be silent in the night, by throwing a stone or clod 
into the bushes where it sits you immediately set it a singing ; or 
in other words, though it slumbers sometimes, yet as soon as it 
is awakened it reassumes its song.* 
LEITER XL To T. PENNANT, Esq. 
DEAR SIR, Selborne, Sept. 2, 1774. 
Before your letter arrived, and of my own accord, I had been 
remarking and comparing the tails of the male and female swal- 
low, and this ere any young broods appeared ; so that there was 
no danger of confounding the dams with their puUi : and besides, 
as they were then always in pairs, and busied in the employ of 
nidification, there could be no room for mistaking the sexes nor 
the individuals of diiferent chimneys the one for the other. From 
all my observations, it constantly appeared that each sex has the 
long feathers in its tail that give it that forked shape ; with this 
difference, that they are longer in the tail of the male than in that 
of the female. t 
Nightingales, when their young first come abroad, and are 
helpless, make a plaintive and a jarring noise ; and also a snap- 
ping 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. 
Svv^ans 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 mysterious.^ 
* Sufficiently intimating-, if other evidence were wanting, that the louder notes of birds are 
those of challenge and defiance. I have known a whitethroat-fanvent to sing loudly and con- 
tinuously after it had heen wounded and brought down wifh the gun.— Ed. 
t They often vary in length in the same individual, and are comparatively very short in the 
young. — Ed. 
t Two species of eels {anguilla) are extremely common throughout the country, a third has 
been discovered in the river Avon, in Hampshae, and a fourth, the grig eel, as it has been 
