San Luis National Wildlife Refuge lies in California’s San Joaquin Valley within the floodplain of Bear Creek, Salt Slough, and the San Joaquin River. It preserves part of a former major Pacific Flyway wintering ground, with wetlands, oxbows, tree-lined channels, and native grasslands. Thousands of wetland acres are sustained by canals and managed to provide natural food for migrating birds. The refuge also protects extensive native grasslands, shrubs, and vernal pools among the Central Valley’s most pristine remaining examples. In winter it supports vast numbers of ducks, along with year-round wood ducks, nesting herons and egrets, many songbirds, hawks, owls, and a reintroduced herd of endangered tule elk.