From 1981-1982. I made 13 monthly bird censuses along a 1.000 m line transect at the northern end of the Departamento del Valle (Colombia), and casual observations throughout the 300 ha surrounding the transect. I recorded 141 species of birds for the total area, of which 42 were counted during the censuses, and only 14 regularly used the pastureland. Similarity indices between months indicated that, on the average, 56.4% of the species were common to all censuses. Both species richness and diversity fluctuated greatly, having a peak posterior to the rainy months at the end of the year and a second after the main rainy season. A large proportion (40.5%) of the resident species in the transect were insectivores. In addition to the basic stock of resident species, this community includes a floating set with similar inputs of forest species from the foothills, floodplain and bamboo forests.