178 The Natural History of Selborne 



reed-sparrow of Ray, the sedge-bird of Mr. Pennant's last publi- 

 cation, p. 1 6 ? 



As to the matter of long-billed birds growing fatter in moderate 

 frosts, I have no doubt within myself what should be the reason. 

 The thriving at those times appears to me to arise altogether from 

 the gentle check which the cold throws upon insensible perspiration. 

 The case is just the same with blackbirds, &c. ; and farmers and 

 warreners observe, the first, that their hogs fat more kindly at such 

 times, and the latter that their rabbits are never in such good case, 

 as in a gentle frost. But when frosts are severe, and of long 

 continuance, the case is soon altered ; for then a want of food soon 

 overbalances the repletion occasioned by a checked perspiration. 

 I have observed, moreover, that some human constitutions are more 

 inclined to plumpness in winter than in summer. 



When birds come to suffer by severe frost, I find that the first that 

 fail and die are the redwing-fieldfares, and then the song-thrushes. 



You wonder, with good reason, that the hedge-sparrows, &c., can 

 be induced at all to sit on the egg of the cuckoo without being 

 scandalized at the vast disproportionate size of the supposititious 

 egg ; but the brute creation, I suppose, have very little idea of 

 size, colour, or number. For the common hen, I know, when the 

 fury of incubation is on her, will sit on a single shapeless stone 

 instead of a nest full of eggs that have been withdrawn : and, more- 

 over, a hen-turkey, in the same circumstances, would sit on in the 

 empty nest till she perished with hunger. 1 



I think the matter might easily be determined whether a cuckoo 

 lays one or two eggs, or more, in a season, by opening a female 

 during the laying time. If more than one was come down out of 

 the ovary, and advanced to a good size, doubtless then she would 

 that spring lay more than one. 2 



1 As a matter of fact, the egg of the cuckoo is scarcely larger than that of the 

 hedge-sparrows and chaffinches in whose nest the mother-bird lays : but the 

 young cuckoo is very voracious, and therefore soon outgrows its small foster-brothers. 

 Cuckoos have not been observed to lay in the nests of birds whose eggs are larger 

 than their own. Their most common host, I think, is the meadow-pipit. ED. 

 2 This is physiologically incorrect. Only one ovum is contained in the oviduct 

 of any bird at one time ; but the cuckoo, as already noted, does lay several eggs in 

 each season. ED. 



