Many salt ponds around the Mediterranean are being either abandoned or converted into aquaculture enterprises, which affects their use by migratory shorebirds. Effective management of salt ponds can improve their attractiveness to birds but requires a better understanding of the shorebirds' response to variations in environmental conditions of the ponds. The main objectives of this study were to analyze the relative importance of different types of salt pond (industrial, traditional and inactive) to shorebirds throughout the tidal cycle, as well as determine the environmental factors that affect the use of salt ponds by shorebirds. Birds were counted during low and high tides on salt ponds in the Guadiana estuary, southeast Portugal. Simultaneously, the environmental conditions of each of the 212 pans studied were recorded and their importance analyzed using logistic regression models. Although more birds used the salt ponds during the high-tide, many species stayed in the study area during lowtide, suggesting a preference to feed on salt ponds as compared to tidal flats. Industrial salt ponds were preferred by most of the species. Water depth, salinity and area were major factors in explaining the presence of the shorebirds and, hence, are the most important environmental variables to take into consideration when devising management plans for salt ponds.