Coccyzus americanus

Banks (1988) concluded that morphological differences among geographic samples were inadequate to justify the recognition of the eastern (C. a. americanus) and western (C. a. occidentalis) subspecies. Franzreb and Laymon (1993, cited in USFWS 2000) found small but statistically significant differences between the two groups and, while stating that the evidence for recognition of the two subspecies was equivocal, recommended retaining them until further studies provided more information. California Department of Fish and Game evidently disagrees with this conclusion and believes that C. a. occidentalis is worthy of recognition and deserves federal protection as an Endangered species (California Department of Fish and Game 1990). May form a superspecies with C. euleri (AOU 1998).

Widespread and common in core of range. Causes of declines in eastern and central North America unclear, thus it is not certain what actions should be taken to reverse them. Western populations deserve special attention.

The breeding range extends from interior California to southern Idaho, southeastern Montana, the Dakotas, southern Manitoba (rarely), Minnesota, and New Brunswick, and south to southern Baja California, southern Arizona, Coahuila, Chihuahua, Nuevo Leon, Tamaulipas, the U.S. Gulf Coast, and the Florida Keys; sporadically farther south in Mexico and in the Greater Antilles (AOU 1998). The species is uncommon on Cuba, Hispaniola, and Puerto Rico; rare in the Virgin Islands, Jamaica, and northern Lesser Antilles (Saint Martin)m and possibly occurs in the Bahamas and Lesser Antilles (Raffaele et al. 1998). Yellow-billed cuckoos formerly nested in British Columbia, Washington, and Oregon. Based on Breeding Bird Survey data (Sauer et al. 2008), this species is most abundant in the south-central United States (Kansas and Missouri southward to Texas and Mississippi). During the nonbreeding season, yellow-billed cuckoos occur from southern Central America (rare and local in Costa Rica) and northern South America (and Trinidad and Tobago) south to eastern Peru, Bolivia, and northern Argentina (AOU 1998) and occur rarely in the West Indies (Raffaele et al. 1998).

This species is represented by hundreds of occurrences (subpopulations).

In western North America, large declines in distribution and abundance have occurred as a result of loss, degradation, and fragmentation of riparian habitat (see information for subspecies occidentalis). Causes of decline in central and eastern North America are uncertain.