LETTER IV. 



'To the same. 



SELBORNE, Feb. ityh, 1770. 



EAR SIR, Your observation that "the cuckoo 

 does not deposit its egg indiscriminately in the 

 nest of the first bird that comes in its way, but 

 probably looks out a nurse in some degree con- 

 generous, with whom to intrust its young," is 

 perfectly new to me ; and struck me so forcibly, 

 that I naturally fell into a train of thought that 

 led me to consider whether the fact was so, and what reason there 

 was for it. When I came to recollect and inquire, I could not find 

 that any cuckoo had ever been seen in these parts, except in the 

 nest of the wagtail, the hedge-sparrow, the titlark, the whitethroat, 

 and the redbreast, all soft-billed insectivorous birds. The excellent 

 Mr. Willughby mentions the nest of the Palumbus (ring-dove), and 

 of the fringilla (chaffinch), birds that subsist on acorns and grains, 

 and such hard food : but then he does not mention them as of his 

 own knowledge ; but says afterwards that he saw himself a wagtail 

 feeding a cuckoo. It appears hardly possible that a soft-billed bird 

 should subsist on the same food with the hard-billed : for the former 

 have thin membranaceous stomachs suited to their soft food ; while 



