Yellow-billed cuckoos are long-tailed, slender birds that stay well hidden among deciduous woodlands. They usually sit completely still, even hunching up their shoulders to hide their crisp white underparts, while hunting for large caterpillars. On a shaded perch, bold white spots on their tail’s underside often are the most visible feature. Their stuttering, croaking calls, heard over a great distance, often are heard on humid, hot afternoons, and so this bird is often called the "rain crow," as if it is calling for rain.
Yellow-billed cuckoos inhabit Nearctic and Neotropical regions. The areas where they breed are eastern North America, southeast Canada, the Greater Antilles and northern Mexico. They winter mainly in South America (Peru, northern Argentina and Bolivia). These birds prefer open woodlands with a dense shrub layer and clearings. Often they are found in woodlands near lakes, rivers or streams. In North America, they prefer such habitats as old fruits orchards, abandoned farmland, dense thickets and successional shrubland. In winter, they frequent tropical habitats with a similar structure, like scrub forest and mangroves.
Yellow-billed cuckoos live alone or in pairs in the breeding season. It is thought that they may be territorial. They are patient feeders, and will sit motionless on hidden perches, frequently with their shoulders hunched in order to disguise their white belly and chest while waiting for their prey to move. They will glean insects from leaves, also hopping to the ground to pursue frogs, lizards and grasshoppers, or to sally out in the manner of a flycatcher to seize a flying insect. These birds are fully migratory, flying at night in either small or large flocks. Aside from migration, these birds are typically diurnal. Individuals mainly use vocalizations to communicate. Generally silent during winter and migration, they vocalize regularly early in the breeding season before chicks fledge. They can make at least 6 sounds, and use them for a wide range of social situations.
This species is probably monogamous. Males may court by offering nest materials such as sticks to a female, and feeding her. Breeding starts in mid- to late May. Populations typically breed once a year, though some populations in the east may produce two broods per breeding season. Both adults build the nest of twigs, lined with dried leaves and roots, and edged with pine needles. 1 to 5 light blue eggs are laid (usually 2 or 3) and incubation begins after the first egg has been laid. Incubation is by both parents, and runs for 9 to 11 days. The chicks are altricial when they hatch, and are brooded frequently by the parents for about the first week. Both parents feed them, and they begin to leave their nest at 7 to 9 days old and begin to fly at 21 days old. Soon after that they disperse from the nest. Most yellow-billed cuckoos reach maturity at the age of 1.
Yellow-billed cuckoos are commonly found within parts of their range. However, in recent years populations have been declining throughout much of their range, most likely because of habitat loss and fragmentation. Further threats to these populations include poisoning from environmental contaminants such as pesticides and collision with tall buildings and towers during their nocturnal migration.
According to the What Bird resource, the total population size of the Yellow-billed cuckoo is around 9.2 million individuals. Currently this species is classified as Least Concern (LC) on the IUCN Red List, but its numbers today are decreasing.