212 
FRANCIS H. HFRRICK 
stomachs of adults of both species, gathered from a wide area, 
and chiefly between May and October. Their diet was found 
to consist almost exclusively of insects, and in great variety, one 
stomach only containing vegetable food, and this but two berries 
of the rough-leaved cornel, all other vegetable debris coming from 
the great numbers of caterpillars of lepidoptera which devour 
vegetable tissue. 
Much has been written to show that the lapse of the brooding 
instinct in Cuculus canorus, and even the small size of its eggs are 
due to the innutritions character of its food. Thus it has been 
maintained that their ordinary caterpillar-diet contained so little 
nourishment that it was necessarily taken in great quantities, 
with the result of distending the stomach, imperfectly nourishing 
the growing eggs, and leaving no time for the process of incuba- 
tion. It is unnecessary to dwell upon the absurdity of these 
statements, but this is probably the first time that reduction in the 
size of the egg, or abbreviation in development, has been directly 
attributed to the nature of the food. The kind of reasoning em- 
ployed by advocates of this theory is fallacious at every point, and 
is contradicted not only by the fact that many brooding species 
live like the non-brooding European cuckoo on a miscellaneous 
insect diet, but by the more significant circumstance than the 
American cuckoos eat the same kind of food, and yet lay large 
eggs, and rear their own young. 
B. Food of young cuckoos 
When the supply is abundant, birds as a rule, feed their young 
such food as in their habitual methods of search they find and eat 
themselves. The food of nestling cuckoos is illustrated in tables 
3-5, in which the daily fare is shown to consist, like that of the 
adults, of a miscellaneous assortment of insects, no fruit whatever 
having been served at their nests. Smooth larvae represented 44 
per cent of the total food, and hairy caterpillars and adult lepi- 
doptera about 5 per cent each, while grasshoppers, which Beal 
found to constitute 30 per cent of the adult pabulum, furnished 
27 per cent in the case of these young. The smooth larvae were 
