242 CLASS AVES. 



parents carried to the nest forty caterpillars in an hour. He 

 supposed the sparrows to enter the nest only during twelve 

 hours in the day, which would cause a daily consumption 

 of four hundred and eighty caterpillars ; and this average 

 gives three thousand three hundred and sixty caterpillars 

 extirpated, weekly, from a garden. But the utility of these 

 birds is not limited to this circumstance alone ; for they 

 likewise feed their young ones with butterflies, and other 

 winged insects, each of which, if not destroyed, would be the 

 parent of hundreds of caterpillars. 



On this calculation of Mr. Bradley, we shall only observe, 

 that the premises on which it is grounded, appear, to say the 

 least of them, suspicious. He observed the sparrows for one 

 hour only : they must have consumed the entire of that hour 

 in going from and to the nest, in bringing such a number 

 of caterpillars. Now, it really appears too much to sup- 

 pose, that the birds consumed twelve hours out of the twenty- 

 four in such operations. Besides, the number of caterpillars, 

 supposed to be daily eaten by the young, which, probably, 

 were not more than three or four in number, shocks probability, 

 even taking the assistance of the parents into consideration. 

 The caterpillar in general is not so very small a morsel, 

 in proportion to the size of the birds, and it would appear 

 that such a quantity must overload their stomachs, and occa- 

 sion death. In fact, all such calculations must of necessity, 

 be liable to great error ; yet we cannot help thinking, on 

 the whole that that of the Frenchman has the least fallacy 

 about it of the two. 



The doctrine of compensation itself, is liable to much diffi- 

 culty. Birds, by destroying insects, make up for the da- 

 mage they themselves do to the fruits of the earth. Granted. 

 But let us carry this a little farther. It is allowed on all 

 hands, and, indeed, this defence of their destroyers pre- 

 supposes it, that insects do, even in their diminished numbers, 



