Swan Lake National Wildlife Refuge, a 10,795-acre reserve in north-central Missouri near the confluence of the Grand and Missouri rivers, was established in 1937 to provide nesting, resting, and feeding habitat for waterfowl, especially ducks. After its purchase, the Civilian Conservation Corps helped shape the refuge by creating wetlands, building roads and structures, and starting a farming program. Although it also sought to preserve prairie chickens, insufficient grassland prevented a lasting population. The refuge is best known for its birdlife, with 241 avian species observed, and it became a major wintering area for Canada geese and an important regional stop for migratory birds.