Cuckoos are known worldwide for their bizarre haunts and habits, and the Yellow-billed Cuckoo is no exception. Furtive, retiring, and watchful by nature, this species' presence may be first revealed by its hollow, wooden call: ka-ka-ka-ka- kow-kow-kow-kow-kowlp-kowlp-kowlp . It has been dubbed the "Raincrow" because of its apparent tendency to call more frequently on cloudy days, although its proficiency as predictor of weather has never been demonstrated.
The summer distribution of the Yellow-billed Cuckoo ranges throughout much of the United States, southeastern Canada, Greater Antilles, and Mexico, but range boundaries have been confused by recurrent observations of nonbreeding individuals away from breeding sites. Vagrants are not infrequent on Atlantic shores and prairies in Canada, and occasionally wander as far as Alaska and western Europe. Although generally considered a neotropical migrant, some southern populations may prove to be sedentary. Furthermore, immature cuckoos collected in South America in summer suggest isolated breeding sites at tropical latitudes.
Like other cuckoos, the breeding behavior of the Yellow-billed Cuckoo is peculiar. The onset of breeding is apparently correlated with an abundant local food supply. Once initiated, the breeding cycle is extremely rapid, and requires only 17 days from egg-laying to fledging of young. Bursting feather sheaths allow nestlings to become fully feathered within two hours. In addition, the Yellow-billed Cuckoo and its congener, the Black-billed Cuckoo (Coccyzus erythropthalmus), are the only known facultative, interspecific brood parasites among altricial birds. At least 11 passerine species have been used as hosts, most frequently the American Robin (Turdus migratorius), Gray Catbird (Dumetella carolinensis), and Wood Thrush (Hylocichla mustelina). Although the production of extra eggs has been shown, in some cases, to coincide with periodic outbreaks of caterpillars and cicadas, behavioral and physiological mechanisms controlling parasitism remain obscure. Coupled to this mystery is evidence to support the selection of hosts based on egg color, not unlike egg mimicry exhibited by obligately parasitic Old World cuckoos. The Yellow-billed Cuckoo has also been observed to breed cooperatively in California, with at least three or four adults tending a single nest.
Unfortunately, the future of the Yellow-billed Cuckoo is uncertain. Populations are declining precipitously throughout its distribution. Western populations have suffered severe range contractions during the twentieth century, and are already extirpated from British Columbia, Washington, Oregon, and possibly Nevada. In California, this cuckoo once numbered more than 15,000 pairs, but the population has been reduced to about 30 pairs in less than 100 years due to the destruction of preferred riparian habitat and to pesticide use. Surprisingly, the critically imperiled western population has yet to receive adequate federal and state protection due primarily to controversy surrounding the validity of its subspecies status. Immediate conservation intervention is essential to ensure that the Raincrow continues to be heard calling among western cottonwoods.
Few aspects of Yellow-billed Cuckoo life history have been adequately studied. Feeding and nesting behavior is described by Hamilton and Hamilton (1965) and Laymon (1980), with detailed observations of single nests reported by Preble (1957) and Potter (1980). In addition, some anomalous breeding behaviors have been examined (Nolan and Thompson 1975, Fleischer et al. 1985, Hughes 1997). The distribution and status of western populations has been quantified by Gaines and Laymon (1984), Howe (1986), Groschupf (1987), and Laymon and Halterman (1987).
Help author an account about this species from a Neotropical perspective.