104 THE NATURAL HISTOEY 



If this severe season does not interrupt the regularity of the 

 summer migrations, the blackcap will be here in two or three 

 days. I wish it was in my power to procure you one of those 

 songsters ; but I am no birdcatcher ; and so little used 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. 320 ; or was it the less 

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

 tion, 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 a want of food soon overbalances the repletion 

 occasioned by a checked perspiration. I have observed, more- 

 over, 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 sup- 

 posititious egg ; 1 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 withdrawn : and, moreover, a hen-turkey, in the same circum- 

 stances, would sit on in the empty nest till she perished with 

 hunger. 



I think the matter might easily be determined whether a 



1 [It is singular that White should have written as if he were not aware of the 

 very small size of the cuckoo's egg in proportion to that of the bird. In many 

 cases it is not easy at a glance to distinguish the supposititious egg ; for which 

 reason it is probable that the blue eggs which the cuckoo is now known sometimes 

 to lay often escape detection in the nests of the hedge-sparrow.] 



