VOL. LXXVIII.] PHILOSOPHICAL TRANSACTIONS.* 43/ 



The circumstance of the young cuckoo's being destined by nature to throw 

 out the young hedge-sparrows, seems to account for the parent-cuckoo's dropping 

 her egg in the nests of birds so small as those I have particularized. If she 

 were to do this in the nest of a bird which produced a large eggj and conse- 

 quently a large nestling, the young cuckoo would probably find an insurmount- 

 able difficulty in solely possessing the nest, as its exertions would be unequal to 

 the labour of turning out the young birds.* Besides, though many of the 

 larger birds might have fed the nestling cuckoo very properly, had it been com- 

 mitted to their charge, yet they could not have suffered their own young to 

 have been sacrificed, for the accommodation of the cuckoo, in such great num- 

 ber as the smaller ones, which are so much more abundant; for though it would 

 be a vain attempt to calculate the numbers of nestlings destroyed by means of 

 the cuckoo, yet the slightest observation would be sufficient to convince us that 

 they must be very large. Here it may be remarked, that though nature permits 

 the young cuckoo to make this great waste, yet the animals thus destroyed are 

 not thrown away or rendered useless. At the season when this happens, great 

 numbers of tender quadrupeds and reptiles are seeking provision ; and if they 

 find the callow nestlings which have fallen victims to the young cuckoo, they 

 are furnished with food well adapted to their peculiar state. 



It appears a little extraordinary, that 2 cuckoo's eggs should ever be deposited 

 in the same nest, as the young one produced from one of them must inevitably 

 perish ; yet I have known 2 instances of this kind, one of which I shall relate. 

 June 27, 1787, 1 cuckoos and a hedge-sparrow were hatched in the same nest 

 this morning ; one hedge-sparrow's egg remained unhatched. In a few hours 

 after, a contest began between the cuckoos for the possession of the nest, which 

 continued undetermined till the next afternoon ; when one of them, which was 

 somewhat superior in size, turned out the other, together with the young hedge- 

 sparrow and the unhatched egg. This contest was very remarkable. The com- 

 batants alternately appeared to have the advantage, as each carried the other 

 several times nearly to the top of the nest, and then sunk down again, oppressed 

 by the weight of its burden ; till at length, after various efforts, the strongest 

 prevailed, and was afterwards brought up by the hedge-sparrows. 



I come now, to consider the principal matter that has agitated the mind of the 

 naturalist respecting the cuckoo ; why, like other birds, it should not build a 

 • I have known an instance in which a hedge-sparrow sat on a cuckoo's egg and one of her own. 

 Her own egg was hatched 3 days before the cuckoo's, when the young hedge-sparrow had gained 

 such a superiority in size that the young cuckoo had not powers sufficient to lift it out of the nest till 

 it was 2 days old, by which time it was grown very considerably. This egg was probably laid by 

 the cuckoo several days after the hedge-sparrow had begun to sit ; and even in this case it appears 

 that its presence had created the disturbance before alluded to, as all the hedge-sparrow's eggs were gone 

 except one. — Orig. 



