Yellow-billed Cuckoo

The Yellow-billed Cuckoo is generally the rarer of New Hampshire’s two cuckoo species, and less commonly found north of the White Mountains. Like its black-billed relative it is a specialist on hairy caterpillars, and it will extend its range north when species like tent caterpillar or Spongy Moth are abundant. It is a little more nomadic than the black-billed, and thus quicker to respond to caterpillar infestations. It is during such infestation years when Yellow-billed may be the more common of the two species, and after the outbreak has subsided it may be another 4-5 years before it returns to an area.

Because of these prey-based fluctuations, it’s hard to assess cuckoo populations, even more so because they tend to occur in low densities. Recent trends suggest a short-term increase in New Hampshire for the Yellow-billed Cuckoo after decades of ups and downs. This contrasts with the status of the species away from the Northeast. In most of the Southeast, Great Plains, and southwest it is in decline, and severe losses of riparian habitat in the latter have resulted in that population being listed as Threatened under the Endangered Species Act.

Not to be confused with their European relatives, North American cuckoos are not brood parasites that lay their eggs in other birds’ nests – at least usually. They are known to dump eggs into other cuckoo nests (both Black-billed and Yellow-billed) and more rarely in those of larger songbirds such as robins and catbirds, but these instances are rare and have not been subject to detailed study. No matter where the eggs are laid, they have a short incubation period for a bird the size of a cuckoo: nine days versus 12-14 days for a robin. Even more remarkably, the young develop very quicky and leave the nest only eight days later (again, 13 days for a robin). Although fully feathered, they remain flightless at this stage but can clamber around in branches rapidly.