Yellow- billed Cuckoo 
59 
Nest 
and Eggs 
a nest for itself, but quietly steals away and deposits its eggs secretly, 
one at a time, in the nests of other birds. There the eggs are incubated 
and the young are reared by foster parents. While the Cuckoo thus 
saves itself the labor of building a nest, and the anxiety of caring for 
its young, it suffers from an unpleasant notoriety possessed by few 
other birds. In this country the black Cowbird has the same parasitic 
habit. 
Our Yellow-billed Cuckoo has learned the art of nest-building but 
poorly, the cradle in which the young are reared being little more than 
a mere platform of twigs. Indeed, so thin and frail a structure is it that 
often the eggs may be counted through the nest from beneath. It is 
usually placed on the sheltered limb of a tree or 
among thick vines in hedge-rows growing along 
streams, and in orchards or groves. The eggs are 
nearly an inch and a quarter long, and about three-fourths as wide. 
They number from two to four, and in color are greenish-blue. Many 
birds lay their eggs, one each day, with great regularity, until the full 
number has been reached. The Cuckoo, however, often allows a few 
days to pass after she begins sitting on some of the eggs before the 
others are deposited. Thus a young bird, an incubated egg, and a 
freshly laid egg are sometimes found in the same nest. 
Among the branches of our fruit-trees we may sometimes see large 
webs which have been made by tent-caterpillars. An invading host 
appears to have come and pitched its tents among the boughs on all sides. 
These caterpillars are destructive to trees, and the Cuckoos do us a 
great service by coming often to raid the encampment. They pull the 
little hairy intruders out of their tents by hundreds and eat them. So 
many are eaten by these birds that often their stomachs are found to be 
thickly coated with a layer of caterpillar-hairs. Cuckoos also eat grass- 
hoppers and various kinds of flies. 
The Biological Survey of the United States Department of Agri- 
culture has, for many years, been studying the feeding-habits of wild 
birds, with the object of determining their relationship 
to mankind. Dr. F. E. L. Beal, of this Bureau, in his 
paper on the relation of Cuckoos to agriculture, says : 
“The insect-food of Cuckoos consists of beetles, grasshoppers, cicadas, 
bugs, ants, wasps, flies, caterpillars, and spiders, of which grasshoppers 
and caterpillars constitute more than three-fourths. In 129 stomachs 
examined, 2,771 caterpillars were found, or an average of 21 in each. 
In May and June, when tent-caterpillars are defoliating fruit-trees, these 
insects constitute half of the Cuckoo’s food. One stomach was so full 
that the bird had evidently devoured the whole tent-colony, as there were 
several hundred in the stomach. This diet of hairy caterpillars has a 
curious effect on the bird’s stomach, the lining of which is often pierced 
by so many hairs as to be completely furred, the membrane itself being 
almost entirely concealed. It seems hardly possible to overestimate the 
value of the Cuckoo’s work. All caterpillars are harmful, many of them 
Great 
Utility 
