Western populations of the Yellow-billed Cuckoo (Coccyzus americanus occidentalis) have decreased and the species’ future is uncertain. Despite this, the basic habitat requirements of this species are largely unknown. Some of the largest concentrations of the western Yellow-billed Cuckoo occur within the Sonoran Joint Venture boundaries, including along the Salt and the San Pedro rivers. We currently have funding from the Salt River Project to conduct cuckoo surveys during the 2003 breeding season. The areas to be surveyed are located in the Salt River, including around Roosevelt Lake, and the Lower San Pedro River. We propose to expand upon this work by using radio-telemetry to track individual Yellow-billed Cuckoos in order to better determine cuckoo breeding habitat and food requirements. Through this project we will: (1) identify habitat requirements of the western Yellow-billed Cuckoo, a Candidate Species under the Endangered Species Act; (2) inventory riparian habitat in the Salt River and the Lower San Pedro River and identify areas of Yellow-billed Cuckoo habitat and potential habitat; and (3) identify and survey riparian restoration areas for Yellow-billed Cuckoo presence/absence and breeding and compare restoration area habitat characteristics with known cuckoo habitat.