Description of Program and/or Project a. Background: The Cooperative Ecosystem Studies Units (CESU) Network is a national consortium of federal agencies, academic institutions, tribal, state, and local governments, nongovernmental conservation organizations (300 partners). The Desert Southwest Cooperative Ecosystem Studies Unit (DSCESU) is a cooperative network, transcending political and institutional boundaries, which creates innovative opportunities for research, education, and technical assistance in support of the management and stewardship by partner agencies of the Desert Southwests natural, cultural, and social resources. The DSCESU has a unique collaborative relationship with research scientists, end users of research products, the public, and educators who are trained to bridge the gap between researchers, science users and educators. The western yellow-billed cuckoo (YBCU, Coccyzus americanus) is listed as threatened under the Endangered Species Act of 1973. It is a neo-tropical migrant that is associated with habitats such as wetlands and riparian corridors with an abundant cottonwood-willow mix similar to those habitats found on the Big Sandy and Santa Maria Rivers in western Arizona. Occupancy for the adjacent Bill Williams River has been confirmed. The northern Mexican Gartersnake (NMGS; Thamnophis eques), is listed as threatened under the Endangered Species Act of 1973. Recent surveys by AGFD biologists have confirmed NMGS occupancy on the Big Sandy River and adjacent Bill Williams River although the extent of suitable and/or occupied habitat is currently unclear. The southwestern willow flycatcher (SWWFL, Epidonax traillii extimis), is listed as endangered under the Endangered Species Act of 1973. Surveys have confirmed SWWFL occupancy on the Big Sandy River, at the confluence of the Big Sandy and Santa Maria Rivers, and the adjacent Bill Williams River although the extent of suitable and/or occupied habitat is currently unclear. The distribution of the YBCU, NMGS, and SWWFL is unclear on the Big Sandy and Santa Maria Rivers. The purpose of this project is to survey for the presence of these species on sections of the Big Sandy and Santa Maria rivers. Data from this project will provide YBCU, NMGS, and SWWFL habitat and population distribution data to land managers so that informed decisions concerning future adaptive management strategies and Endangered Species Act compliance can occur. b. Objectives: The objective of this program is as follows; 1. Document the presence of YBCU on sections of the Big Sandy and Santa Maria rivers using standardized survey methodology 2. Document the presence of NMGS on sections of the Big Sandy and Santa Maria rivers using standardized survey methodology 3. Document the presence of SWWFL on sections of the Big Sandy and Santa Maria rivers using standardized survey methodology