COMMON CUCKOO. 185 



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 flies, 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, even one of the 

 earliest, would be fit to provide for itself before its parent 

 would be instinctively directed to seek a new residence, and 

 be thus compelled to abandon its young one ; for old 

 Cuckoos take their final leave of this country the first week 

 in July." This, however, I may here remark, is not always 

 the case. The notes of the male have been heard as late as 

 the end of July. The males arrive before the females in 

 spring, and probably leave us before them in summer. The 

 young birds of the year do not go till September ; and Mr. 

 Rodd of Penzance sends me word that he has known them 

 remain in Cornwall till October. 



M. Temminck, in the Supplement to the first volume of 

 his Manual, mentions that M. Schlegel, one of the Assistant 

 Naturalists in the Museum at Leyden, had in a memoir ad- 

 dressed to the Natural History Society of Harlem, supplied 

 details of great interest on the probable causes which induce 

 the Common Cuckoo, and all those species which deposit 

 their eggs in the nests of small insectivorous birds, not to 

 burthen themselves with the hatching or the feeding of their 

 young. " The principal cause alleged in the case of the 

 Cuckoo, is the particular nature and effect of its food produ- 

 cing an enlargement of the stomach, which appears to influence 

 the developement of the eggs in the ovarium ; these are 

 known to be very small, and the bird lays at intervals of six 

 or eight days." 



Whatever influence may really be attributable to the 

 nature or quantity of the food taken by the Cuckoo, there is 

 good reason to believe that it does produce its eggs at inter- 



