River otters nearly vanished from Missouri by the early 1900s, trapped and drained out of most of the state before wildlife agencies reintroduced them starting in the 1980s. The recovery shows in these records: Mingo National Wildlife Refuge, Big Oak Tree State Park, and Swan Lake National Wildlife Refuge all protect the sloughs, oxbows, and river backwaters otters need for fish, crayfish, and cover.
Sightings cluster in January and again in May, bracketing a period when otters are more visible moving between icy ponds and open water, then again during spring dispersal. iNaturalist accounts for most of the record set (152 of 259 combined), which tracks with otters being an easy, exciting species to photograph when one surfaces near a boat launch or bridge. NatureServe ranks Missouri’s population S5, Secure, reflecting how thoroughly the reintroduction succeeded. The numbers here still describe where people spotted otters, not how many now live along the state’s rivers.
