Lewis and Clark National Wildlife Refuge, near the mouth of the Columbia River, provides wintering and resting areas for an estimated 1,000 tundra swans, 5,000 geese, and 30,000 ducks. Other species include shorebirds and bald eagles. Estuary waters provide vital food resources for juvenile salmon as they pause to become acclimated to salt water before entering the Pacific Ocean. Bald eagles are present year-round; there are 30 to 35 active nest sites.