Crossbill 



LETTER VIII. 



To the same. 



SELBORNE, Dec. zotfi, 1770. 



R SIR, The birds that I took for aberdavines 

 were reed-sparrows (Pas seres tor quart}. 



There are doubtless many home internal migra- 

 tions within this kingdom that want to be better 

 understood : witness those vast flocks of hen 

 chaffinches that appear with us in the winter 

 without hardly any cocks among them. Now 

 was there a due proportion of each sex, it should seem very improb- 

 able that any one district should produce such numbers of these 

 little birds ; and much more when only one-half of the species 

 appears ; therefore we may conclude that the Fringill^e ccelebes^ for 

 some good purposes, have a peculiar migration of their own in 

 which the sexes part. Nor should it seem so wonderful that the 

 intercourse of sexes in this species of bird should be interrupted in 

 winter ; since in many animals, and particularly in bucks and does, 

 the sexes herd separately, except at the season when commerce is 

 necessary for the continuance of the breed. For this matter of the 

 chaffinches see "Fauna Suecica," p. 85, and "Systema Naturae," 

 p. 318. I see every winter vast flights of hen chaffinches, but none 

 of cocks. 



