LETTER XL 



TO THE SAME 



SELBORNE, Sept. z>id, 1774. 



DEAR SIR, Before your letter arrived, and of my own 

 accord, I had been remarking and comparing the tails of 

 the male and female swallow, and this ere any young broods 

 appeared ; so that there was no danger of confounding the 

 dams with their pulli : 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 different 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. 



Nightingales, when their young first come abroad, and 

 are helpless, make a 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. 1 



The grasshopper-lark chirps all night in the height of 

 summer. 2 



Swans turn white the second year, and breed the third. 



Weasels prey on moles, as appears by their being some- 

 times caught in mole-traps. 



Sparrow-hawks sometimes breed in old crows' nests, 3 

 and the kestril in churches and ruins. 



1 This is the alarm-note of most of the Warblers. [R- B. S.] 

 * Salicaria locustclla, see Letter XVI (antea, p. 63). [R. B. S.] 

 3 So do Kestrels, which, more often than not, appropriate the old nest of some 

 other bird, whereas Sparrow-hawks as a rule build their own nest. [R. B. S.] 



