Small wetlands in the developing world are disappearing due to bad management and urban growth, thereby threatening the birdlife that inhabits them. The Huacho-Hualmay-Carquin wetland is located on Peru’s central coast and it has recently begun to be studied; however, it is already losing ground to urbanization and public beachside development. Twelve bird censuses (with two simultaneous transect lines: “supralittoral” and “urban”) were conducted, and bird diversity and its correlation with two thermal-related oceanic parameters of the South Pacific (SST and ICEN) were calculated. Seventy-eight bird species were found, with abundances as high as 19,000 individuals. Species richness and abundance were higher in the supralittoral transect, while diversity was higher in the urban transect. We found correlations between the alpha diversity and abundance with both the SST and ICEN. This ecosystem exhibits high bird diversity, and our study demonstrates the importance of studying small wetlands as means of developing better management and conservation strategies in the region.