Two species of cuckoos are common In the United States east of the Great
Plains, the yellow-billed cuckoo[60] (fig. 23) and the black-billed
cuckoo,[61] and in the West a relative of the yellow-bill, the California
cuckoo,[62] ranges from Colorado and Texas to the Pacific coast. While
the two species are quite distinct, the food habits of the yellow-bill
and the black-bill do not greatly differ and their economic status is
practically the same.
[60] _Coccyzus americanus_.
[61] _Coccyzus erythyropthalmus_.
[62] _Coccyzus americanus occidentalis_.
Examination of 155 stomachs has shown that these species are much given
to eating caterpillars, and, unlike most birds, do not reject those
covered with hair. In fact, cuckoos eat so many hairy caterpillars that
the hairs pierce the inner lining of the stomach and remain there, and
often when the stomach is opened it appears to be lined with a thin
coating of fur.
[Illustration: Fig. 23.--Yellow-billed cuckoo. Length, about 12 inches.]
An examination of the stomachs of 46 black-billed cuckoos, taken during
the summer months, showed the remains of 906 caterpillars, 44 beetles,
96 grasshoppers, 100 sawflies, 30 stinkbugs, and 15 spiders. In all
probability more individuals than these were represented, but their
remains were too badly broken for recognition. Most of the caterpillars
were hairy, and many of them belong to a genus that lives in colonies and
feeds on the leaves of trees, including the apple tree. One stomach was
filled with larvæ of a caterpillar belonging to the same genus as the
tent caterpillar, and possibly to that species. Other larvæ were those
of large moths, for which the bird seems to have a special fondness. The
beetles were for the most part click beetles and weevils, as well as a
few May beetles. The sawflies were contained in two stomachs, one of
which held no less than 60 in the larval stage.
Of the yellow-billed cuckoo, 109 stomachs (collected from May to October)
were examined. They contained 1,865 caterpillars, 93 beetles, 242
grasshoppers, 37 sawflies, 69 bugs, 6 flies, and 86 spiders. As in the
case of the black-billed cuckoo, most of the caterpillars belonged to
hairy species and many of them were of large size. One stomach contained
250 American tent caterpillars; another 217 fall webworms. The beetles
were distributed among several families, all more or less harmful to
agriculture. In the same stomach which contained the tent caterpillars
were 2 Colorado potato beetles; in another were 3 goldsmith beetles, and
remains of several other large beetles. Besides the ordinary grasshoppers
were several katydids and tree crickets. The sawflies were in the larval
stage, in which they resemble caterpillars so closely that they are
commonly called false caterpillars by entomologists. The bugs consisted
of stinkbugs and cicadas, or dog-day harvest flies, with the single
exception of one wheel bug, which was the only useful insect eaten.