RESUMEN
We determined the taxonomic composition and spatial-temporal distribution of aquatic and raptor birds in a freshwater artificial pond of El Centenario, Baja California Sur, MÚxico, during 24 biweekly censuses (April, 1998 to March, 1999). The pond is particularly attractive for birds because of its variety of food items. A total 25,563 records of 69 species were done, among them the first report of Chlidonias niger and Phalaropus tricolor for the region. Species richness and abundance were determined for the migrant component, mostly Anatidae (16 species and 55.6 of the total abundance) and shorebirds (18 species and 13.3). The greater number of species and individuals was in C the deepest and more heterogeneous section of the pond. The most important species was Oxyura jamaicensis (30 of the total observed individuals), with highest abundance in the peninsula. The artificial pond presented an atypical and distinct ornithological composition because it is located in an arid region, and acts as a resting site for migrant birds. The site included species that usually live in freshwater and coastal areas, a characteristic reflected in their high richness. It contributes noticeably to the local avian biodiversity.