Twenty four bird identification and counting campaigns were carried out at Estero de Punta Banda, Baja California, Mexico between March 2004 and March 2005, in six representative environmental units. Thirtyfive bird families were registered, including 104 species. Sixtyfour species were associated with aquatic environments. Both, aquatic and terrestrial communities showed clear temporal patterns with three groups associated with seasonal changes. Twelve of these species are listed as protected in the Mexican environmental legislation. We found evidences of the reproductive success of the Clapper Rail and the Blacknecked Stilt populations in disturbed areas. These results indicated that the Estero de Punta Banda remains an important reproductionfeeding area for many resident and migratory birds. However, the rapid urban development of the City of Ensenada, water pollution, and illegal use of its natural resources, threaten the survival of Estero Punta Banda and its bird species.
