VOL. LXXVIII.] PHILOSOPHICAL TRANSACTIONS. 441 



rapid. The chirp is plaintive, like that of the hedge-sparrow; but the sound is 

 not acquired from the foster-parent, as it is the same whether it be reared by the 

 hedge-sparrow, or any other bird. It never acquires the adult note during its 

 stay in this country. 



The stomachs of young cuckoos contain a great variety of food. On dissect- 

 ing one that was brought up by wagtails, and fed by them at the time it was 

 shot, though it was nearly of the size and fulness of plumage of the parent- 

 bird, I found in its stomach the following substances. Flies and beetles of 

 various kinds : small snails, with their shells unbroken : grashoppers : caterpillars : 

 part of a horse-bean : a vegetable substance resembling bits of tough grass, 

 rolled into a ball : the seeds of a vegetable that resembled those of the goose- 

 grass. 



In the stomach of one fed by hedge-sparrows, the contents were almost en- 

 tirely vegetable ; such as wheat, small vetches, &c. But this was the only in- 

 stance of the kind I had ever seen, as these birds in general feed the young 

 cuckoo with scarcely any thing but animal food. However, it served to clear up 

 a point which before had somewhat puzzled me ; for having found the cuckoo's 

 egg in the nest of a green linnet, which begins very early to feed its young with 

 vegetable food, I was apprehensive, till I saw this fact, that this bird would have 

 been an unfit foster-parent for the young cuckoo. The titlark, I observe, feeds 

 it principally with grashoppers. But the most singular substance, so often met 

 with in the stomachs of young cuckoos, is a ball of hair curiously wound up. I 

 have found it of various sizes, from that of a pea to that of a small nutmeg. 

 It seems to be composed chiefly of horse-hairs, and from the resemblance it 

 bears to the inside covering of the nest, I conceive the bird swallows it while a 

 nestling. In the stomachs of old cuckoos I have often seen masses of hair ; 

 but these had evidently once formed a part of the hairy caterpillar, which the 

 cuckoo often takes for its food. 



There seems to be no precise time fixed for the departure of young cuckoos. 

 I believe they go off in succession, probably as soon as they are capable of 

 taking care of themselves ; for though they stay here till they become nearly 

 equal in size and growth of plumage to the old cuckoo, yet in this very state 

 the fostering care of the hedge-sparrow is not withdrawn from them. I have 

 frequently seen the young cuckoo of such a size that the hedge-sparrow has 

 perched on its back, or half-expanded wing, in order to gain sufficient elevation 

 to put the food into its mouth. At this advanced stage, I believe that young 

 cuckoos procure some food for themselves ; like the young rook for instance, 



for instance, before it becomes fully armed with its prickly coat, the little animal jumps up with a 

 sudden spring, and imitates very closely the sound of the word hush ! as we pronounce it in a loua 

 whisper. This disposition is apparent in many other animals.— Orig. 

 VOL. XVI. 3 L 



