150 NATURAL HISTORY 



useql . to birds in a cage, that I fear if I had one it would 

 soon die for want of skill in feeding. 



Was your reed sparrow, which you kept in a cage, the 

 thick-billed reed sparrow of the Zoology, p. 820; or was it 

 the less reed sparrow of Ray, the sedge-bird of Mr 

 Pennants last publication, p. 16 ? 



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 

 , want of food soon over-balances the repletion occasioned 

 by a checked perspiration. I have observed, moreover, 

 that some human constitutions are more inclined to plump- 

 ness 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 disproportioned 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 eggs that have been withdrawn; and, moreover, a hen- 

 turkey, in the same circumstances, would sit on in the empty 

 nest till she perished with hunger. 



I think the matter might easily be determined whether a 

 cuckoo lays one or two eggs, or more, in a season, by open- 

 ing 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?. 



