The Black-billed Cuckoo is a fairly common bird that is heard much more often than it is seen. This secretive bird lives in the dense leafy canopy and feeds on spiny caterpillars. The spines of these caterpillars can become lodged in the cuckoos stomach obstructing digestion so the bird periodically empties it's stomach to clear any such blockage. The decline of this species is probably an indirect result of the chemical control of caterpillar outbreaks throughout their range. They almost exclusively eat caterpillars, especially tent caterpillars and gypsy moths.
Black-billed Cuckoos are birds of woodlands and thickets, including aspen, poplar, birch, sugar maple, hickory, hawthorn, and willow. They tend to occur in more extensive tracts of woods than the Yellow-billed Cuckoo and are more likely to be found in deciduous than coniferous woods. On their South American wintering grounds they live in forest, woodlands, and scrub.
Black-billed Cuckoos eat large insects such as caterpillars, katydids, cicadas, and grasshoppers. They seem to have a particular appetite for large caterpillars—collected individuals have often been found with more than 100 in their stomach at once. Along with Yellow-billed Cuckoo, this is one of only two species found to be more numerous during periodic cicada emergences in a recent analysis. Black-billed Cuckoos occasionally eat eggs of other birds. On their wintering grounds they also eat fruit and seeds.
Black-billed Cuckoos catch prey by sitting motionless for long periods, then running or hopping out at prey. They often shake and hammer caterpillars against a branch to remove their spines before swallowing. Black-billed Cuckoos occasionally lay eggs in nests of other birds, though they do this far less often than the European cuckoo or the Brown-headed Cowbird. Among their hosts are other Black-billed Cuckoos, Yellow-billed Cuckoos, Chipping Sparrows, American Robins, Gray Catbirds, Wood Thrushes, and six other species. Young leave the nest at 6-7 days old, about two weeks before they will be able to fly. Waits motionless for long periods, watching for prey to move.