Effects of the surrounding landscape on waterbird populations in estuarine ecosystems of central Chile

Waterbirds have high potential as bioindicators of the status and functioning of estuarine ecosystems, because they respond to multiple stress factors in a wide range of spatial scales. The objective of this study was to analyze the dependence of the population size of waterbird species with different degrees of association with waterbodies (High: HAW, Low: LAW) on attributes of the surrounding landscape. This was accomplished by long-term monitoring (2006–2015) of the populations of waterbirds in three estuaries of central Chile; the Itata, Mataquito, and Reloca Rivers. We acquired data on the composition and structure of the landscape for each site from satellite sensors (Landsat TM5, ETM + 7 and OLI 8), specifically the normalized difference moisture index (NDMI). We also obtained the covers of grassland and crops, bare soil and shrubland annually (summer) using a supervised classification. Using point-count data (2013–2015) from the landscape surrounding the Itata estuary, we compared the proportion of the population of different species present within and outside the wetland. The negative temporal correlation (p