This bird has the common name of 'raincrow' because its call is often heard in the summer just before a rain storm. It seems to time its egg laying to coincide with outbreaks of favored insects, such as the cicada and hairy caterpillars. The time for incubation and nesting is quite short. At one week of age the chicks are leaving the nest, and at three weeks they are flying and readying for the migration to South America.

Length: 27.9 to 30.4 cm

Physical characteristics: This is a slender bird with a long tail, and the namesake yellow lower mandible. The upperparts are brownish, with rusty colored flight feathers. The chin, breast and belly are white, and there are large white spots on the underside of the tail. Sexes are similar.

Voice: Variable song often includes a loud, low, and slow series of distinct kowlps or a rapid series of kuk-kuk-kuks.

Breeding habitat:
Breeding pairs frequent open woodlands, mostly those with dense undergrowth, riparian woodlands and thickets.

Mating system:
Monogamous; usually one brood is produced, sometimes two in the South. This species will occasionally parasitize other birds' nests when a food source, most notably the cicada, is particularly abundant.

Nest:
The nest is a loose, flimsy platform built of twigs, and lined with dry leaves, pine needles and grass. Both the male and female build the nest.

Eggs:
3 - 5 (usually four) light blue to light green eggs are laid per clutch. 31mm (1.2'').

Chick development:
After 9 - 11 days of incubation by both parents (the male typically remains in the nest at night, while sharing the daytime duties with the female), the chicks are born altricial. They develop quite rapidly; they can hop about after a week and fly by three weeks of age. Fledging usually occurs 5 to 8 days after hatching. If there is a second brood, the male attends to the first, while the female begins on the second.

Diet:
Foraging in the limbs of trees, this species eats primarily insects, particularly the tent caterpillar and other hairy caterpillars. Also some bird eggs, frogs and lizards, and fruits and berries are taken. The young are fed insects regurgitated by the parents.

Parasites:
The feather mite Coraciacarus americanus (Pterolichidae; det. B. M. O. Connor) was collected off of a cuckoo specimen collected near Newfound Gap in June 1959.

The louse Cuculicola coccygii (Osborn) (Philopteridae) was collected off of a cuckoo specimen from Gatlinburg, Tennessee, in May of 1963 (Reeves et al. 2007). Conservation biology:
The Yellow-billed Cuckoo has experienced large-scale population declines throughout its range, but especially in the West, where it is specialized on mature riparian forests. It is quite vulnerable to habitat fragmentation.

Breeding: The Yellow-billed Cuckoo is found primarily in the eastern half of the United States. It is also present in a few scattered locations in the West, in southern California, Arizona and New Mexico, but the numbers are small.

Winter: This species is a neotropical migrant that winters in South America, particularly eastern Peru, Bolivia and northern Argentina.

The Yellow-billed Cuckoo is a fairly common breeding bird species in the Park. This species is a year-round resident in the Park and is most common at elevations below 3,000 feet. A survey of breeding birds in the Park, performed from 1996-1999, ranked Yellow-billed Cuckoo as the 39th most abundant species out of 113 species observed during the breeding season. Estimates from this survey indicate that overall Yellow-billed Cuckoo density in the Park during the breeding season is approximately 0.011 pairs per hectare. Density below 3,000 feet is approximately 0.18 pairs/hectare.

References:

Alsop, F. J. III. 1991. Birds Of The Smokies. Great Smoky Mountains History Association, Gatlinburg, Tennessee.

Bent, A. C. and Collaborators. 1996 - 2002. Yellow-billed Cuckoo, In Life Histories of Familiar North American Birds, ed., Patricia Query Newforth.

Committee on Classification and Nomenclature of the American Ornithologists' Union. 2000. Forty-second supplement to the American Ornithologists' Union Check-list of North American Birds. The Auk 117: 847-858.

Committee on Classification and Nomenclature of the American Ornithologists' Union. 2002. Forty-third supplement to the American Ornithologists' Union Check-list of North American Birds. The Auk 119: 897-906.

Committee on Classification and Nomenclature of the American Ornithologists' Union. 1998. Check-list of North American Birds: the Species of Birds of North America from the Arctic through Panama, including the West Indies and Hawaiian Islands, 7th ed

Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1988. The Birder's Handbook: a Field Guide to the Natural History of North American Birds. Simon and Schuster, Inc., New York.

Elphick, C., J. B. Dunning, Jr., and D. A. Sibley, eds. 2001. The Sibley Guide to Bird Life and Behavior. Alfred A. Knopf, New York.

Gough, G. A., Sauer, J. R., Iliff, M. Patuxent Bird Identification Infocenter. 1998. Version 97.1. Patuxent Wildlife Research Center, Laurel, MD. http://www.mbr-pwrc.usgs.gov/id/framlst/infocenter.html.

Sibley, D. A. 2000. The Sibley Guide to Birds. Alfred A. Knopf, New York.

Stupka, A. 1963. Notes on the Birds of the Great Smoky Mountains National Park. University of Tennessee Press.