GREY CUCKOO. 123 



ill the nests of small Insectivorous birds, not to hatch and rear 

 its young ; and he considers as a principal cause of this pecu- 

 liarity the choice of their ordinary food. The nourishment of 

 the Cuckoo consists almost entirely of very hairy caterpillars, 

 as Bombyx caja, &c., the great bulk of which overloads and 

 singularly inflates the stomach, aiFording at the same time very 

 little nourishment. From this nutrition results a great de- 

 velopment of the whole organ, and an unceasingly returning 

 hunger. The development of the stomach appears to influence 

 that of the eggs in the ovary, which are known to be very 

 small, and which the bird lays at intervals of from six to eight 

 days. The sum of the author's observations is, that the Cuckoo 

 cannot attend to incubation, as it is incessantly occupied in 

 pursuing its prey ; that it cannot, by means of the food which 

 it prefers, satisfy the wants of from four to six voracious young 

 ones, which grow with an astonishing rapidity. The position 

 and great size of the stomach would hinder digestion during 

 the act of incubation ; should incubation take place, the con- 

 stantly recurring need of food would be injurious to the neces- 

 sary development of the young in the egg ; to lay from four to 

 six eggs, the Cuckoo would take so many weeks, and the first 

 egg would be addled before the last were laid. Lastly, the 

 young could not be developed in time to perform their migra- 

 tion, for want of the food necessary for themselves and their 

 parents. If such is actually the cause of this phenomenon in 

 some species of Cuckoos, which I am inclined to believe it to 

 be, it would follow that certain species, which are not sub- 

 jected to this same mode of nourishment, may nestle and attend 

 to incubation exactly like other birds." 



Now, I have found by dissection that the two common Cuckoos 

 of North America have the stomach capable of great distension, 

 and covered internally with hair, so as to be precisely similar to 

 that of the Grey Cuckoo. What then comes of all the above 

 reasoning? Moreover, the Barn Owl has a stomach when 

 collapsed an inch and a quarter long, and when distended three 

 inches, and it occupies precisely the same place as in the Cuckoo, 

 and is larger in proportion to the size of the bird. Yet the 

 Owl incubates, and although it has but a short time to look for 



