THE COMMON CUCKOO. 123 



gition of turning out its companion entirely ceases. The smallnessot' 

 the Cuckoo's egg, which in general is less than that of the House- 

 Sparrow, is another circumstance to be attended to in this surprising 

 transaction, and seems to account for the parent Cuckoo's depositing 

 it in the nests of such small birds only as have been mentioned, if 

 she were to do this in the nest of a bird that produced a larger egg, and 

 consequently a larger nestling, the design would probably be frus- 

 trated ; the young Cuckoo would be unequal to the task of becoming 

 sole possessor of the nest, and might fall a sacrifice to the superior 

 strength of its partners. 



Dr. Jenner observes, that the eggs of two Cuckoos are sometimes 

 deposited in the same nest: he gives the following instance, which 

 fell under his observation. Two Cuckoos and a Hedge-sparrow were 

 hatched in the same nest ; one Hedge-Sparrow's egg remained un- 

 hatched. In a few hours a contest began between the Cuckoos for 

 possession of the nest ; and this continued undetermined till the after- 

 noon of the following day, when one of them, which was somewhat 

 superior in size, turned out the other, together with the young 

 Hedge-Sparrow, and the unhatched egg. The contest, he adds, was 

 very remarkable : the combatants alternately appeared to have the 

 advantage, as each carried the other several times, nearly to the top 

 of the nest, and again sank down, oppressed by the weight of its 

 burden ; till at length, after various efforts, the strongest of the two 

 prevailed, and was afterwards brought up by the Hedge-Sparrow. 



No reason can be assigned, from the formation of this bird, why, in 

 common with others, it should not 'build a nest, incubate its eggs, and 

 rear its own offspring ; for it is in every respect perfectly formed for 

 all these offices. To what cause then may we attribute the above 

 singularities ? May they not be owing to the following circumstances ? 

 the short residence this bird makes in the country where it is des- 

 tined to propagate its species, and the necessity that exists of its 

 producing, during that short residence, a numerous progeny. The 

 Cuckoo's first appearance in England, is about the middle of April : 

 its egg is not ready for incubation till some weeks after its arrival, 

 seldom before the middle of May. A fortnight is taken up by the 

 sitting bird in hatching the egg. The young bird generally continues 

 three weeks in the nest before it can fly, and the foster-parents feed it 

 more than five weeks after this period ; so that, if a Cuckoo should be 

 ready with an egg much sooner than the time pointed out, not a 

 single nestling would be fit to provide for itself before its parent 

 would be instinctively directed to seek a new residence, and be thus 

 mpelled to abandon its offspring ; for the old birds take their final 

 leave of this country the first week in July. 



" There seems (says Dr. Jenner) no precise time fixed for the depar- 

 ture of young Cuckoos. I believe they go off in succession, probably 

 as soon as they are capable of taking care of themselves ; for although 

 they stay here till they become nearly equal in size, and in growth of 

 plumage, to the parent, 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 



