Laguna de Sayula, a seasonal freshwater wetland in Jalisco, western Mexico, supports many resident and migratory bird species, particularly during the dry season (October to May). We documented changes in habitat condition (i.e., water vs. mudflat vs. land cover) and occurrences of 12 waterbird species during the dry season. From October to February, much of the lagoon was covered with water and mudflats, and the avifauna was dominated by resident killdeer (Charadrius vociferus) and migratory long-billed curlew (Numenius americanus). Between March and May, there was significantly less area covered by water and mudflats, and killdeer and the migratory spotted sandpiper (Actitis macularia) were most common. Species tended to co-occur in plots, often in large numbers, suggesting that they were tracking patchy resources within the study area.