8 CUCKOOS AND SHRIKES IN RELATION TO AGRICULTURE. 
to four. The European cuckoo, like our cowbird, lays its eggs in the 
nests of other birds; a reprehensible habit not shared by its American 
cousin, although occasional instances of such parasitism have been 
observed. Our ecuckoos do not ostensibly rear more than one brood in 
a season, but they frequently lay their eggs at intervals, so that the 
young hatch successively, the later eggs being incubated in part by the 
young. 
Three species and two subspecies occur in the United States. Of 
these, one species and one subspecies are restricted almost entirely to 
the southern coast of Florida, and are properly West Indian birds, 
The others occupy practically the whole country, except the plains and 
deserts, though in winter they are found in the extreme southern part 
only. The yellow-billed cuckoo (Coccyzus americanus) breeds from the 
Gulf of Mexico to southern Canada; the black-billed (Coceyzus eryth- 
rophthalmus) ranges still farther north. The northward migration does 
not begin until spring is well advanced, and is usually completed by 
the end of May. Most of the birds leave the Northern States in 
August, but some linger through September and even into October. 
From an economic standpoint cuckoos rank among our most useful 
birds. Their habit of remaining concealed in foliage suggests, and 
close observation proves, that their diet consists for the most part of 
insects—very largely caterpillars—found on trees and shrubs. 
EXAMINATION OF STOMACHS. 
In the laboratory of the Biological Survey 109 stomachs of the yellow- 
billed and 46 of the black-billed cuckoo were examined. All were taken 
between May and October, inclusive, except one of the yellow-billed 
collected in Texas in January. These stomachs were obtained in 
twenty States, the District of Columbia, and Canada, and were fairly 
distributed over the country from Louisiana and Texas to Canada, and 
from Massachusetts to Kansas and Nebraska. A greater number would 
have been desirable, but the contents of those examined were so uni- 
form that it seems fair to infer that they give a reasonably accurate 
idea of the general food of the species. It has been deemed best to 
treat the two species together, since they prove to be very much alike 
in diet. The greatest difference is that the yellow-billed cuckoo eats 
more beetles (Coleoptera) and fewer bugs (Hemiptera). The seasonal 
variation in diet is much less than in most birds. Of the 155 stomachs 
of both species examined, only one contained any vegetable food, 
and this only two berries of the wild rough-leaved cornel (Cornus 
asperifolia). One other stomach contained a bit of rubbish, probably 
taken accidentally with some insect. Drs. C. Wart Merriam and A. K. 
Fisher have seen the yellow-billed species feeding on mulberries in 
Westchester County, N. Y.,! and Dr. I. II. Warren found ‘berries’ in 
‘Annual Report, U.S. Dept, Agriculture for 1890, p. 285, 1891. 
