When early explorers were making their way across what would be southeastern Missouri, they saw a seemingly endless expanse of bottomland hardwood timber and an interconnecting complex of sloughs and St. Francis River oxbows. The New Madrid earthquakes of 1811 and 1812 caused Otter Slough, Fish Slough, Lick Creek and the Glades Swamp to combine into the large wetland now visited by thousands of migrating waterfowl. Otter Slough is one of only a few examples of a cypress/tupelo swamp left in Missouri. The cypress swamp, open marsh and flooded timber provide acorns, natural seeds, tubers and invertebrates, all important waterfowl foods. Corn, wheat, sunflowers and other row crops are all used to maintain an open marsh condition and provide high energy food during winter months to sustain waterfowl during their long, migratory journeys. Duck numbers have exceeded 60,000 and as many as 250,000 snow geese have been recorded on the area. Although the 4,866-acre area is managed primarily for migratory and wintering waterfowl, many wading birds, shorebirds, eagles and wetland mammals make Otter Slough Conservation Area their home.