Yellow-billed Cuckoo
The Yellow-Billed Cuckoo’s (Coccyzus americanus) breeding range once encompassed wooded and desert riparian zones across the United States, southern Canada (Quebec and Ontario), coastal British Columbia, Mexico, and the Caribbean. Deforestation and resultant habitat loss has caused drastic declines across its range. Populations in the western United States are particularly fragmented and the species has been extirpated from British Columbia since the 1920s, underscoring the need for conservation research on the species. Most birds overwinter together in the Gran Chaco region of Argentina and Paraguay, but the strength of migratory connections between their breeding and nonbreeding grounds is unknown.
Within North America, there are two primary subspecies designations that are prominent in the scientific literature. C. a. americanus populates the eastern United States and the Caribbean, and C. a. occidentalis can be found generally west of Amarillo, Texas, as far south as the Mexican states of Sinaloa and Baja California Sur. This western population of Yellow-Billed Cuckoo is currently listed as a threatened distinct population segment by both the federal and California Endangered Species Acts. However, much controversy has surrounded the validity of the subspecies status for the western population, with prior morphological, ecological, and genetic studies often coming to opposite conclusions.
The Bird Genoscape Project team currently aims to clarify the relationship between the western and eastern populations via whole-genome sequencing. With this same data, we will also evaluate various measures of genetic diversity within each subpopulation, such as effective population size and amount of inbreeding. Using a much greater number of gene variants compared to previous genetic and genomic studies, we will be able to measure genetic differentiation and diversity at higher resolution, which will ultimately have an impact on the western population’s federal listing status.
If you are interested in collecting or donating Yellow-billed Cuckoo samples from any location across its range, particularly during the breeding and wintering seasons, please contact Amanda Carpenter to learn more!