A Shrinking Inland Sea: Trends in Avian Populations and Habitats at the Salton Sea

The Salton Sea, a saline lake ecosystem in southern California that is critical for birds along the Pacific migratory pathway, is rapidly changing due to changes in water use and supply. This shrinking Sea supports over 300 species of birds and millions of migratory birds annually. Reduced water inflows since 2017 have lowered water levels and increased salinity, driving ecological change, yet the impacts to birds remain largely unexamined. We analyzed bird population trends (2016–2023), changes in the extent of preferred habitats under different water management regimes, the expansion of emerging vegetation on exposed lakebed, water quality, and macroinvertebrate diversity. Bird population trends reveal both winners and losers: populations of Northern Shovelers, Least and Western Sandpipers, and Black-necked Stilts increased, while populations of American White Pelicans, nonbreeding American Avocets, Double-crested Cormorants, and Ruddy Ducks declined. Increasing shorebird population trends aligned with the expansion of emerging wetland vegetation on exposed lakebed, while decreasing trends in deep water dependent species aligned with the loss of areas of preferred deep-water habitat. Water quality was associated with waterbird abundance, but the effect of biogeochemistry on birds and their prey are not well understood and warrant further research. These findings inform strategic management efforts to sustain and restore habitats at the Salton Sea, with the goal of achieving positive outcomes for birds as wetland and saline habitats across the Western United States remain threatened.