In typical years, hundreds of thousands of snow geese utilize the refuge as a resting and feeding area during their fall migration between Arctic nesting grounds and Gulf Coast wintering areas. These spectacular concentrations are generally seen in November and December; smaller concentrations occur in March and early April. Such large gatherings of snow geese rarely occur elsewhere in Iowa or Nebraska except during the spring northward migration through the Rainwater Basin in central Nebraska. Canada geese show up at DeSoto as well, though in much smaller numbers. Peak populations of 70,000 or more ducks, mostly mallards, also utilize the refuge during fall migration.

Each fall, numerous bald eagles follow the geese to the refuge and out of it again, as the migration proceeds south. Some eagles remain around the refuge all winter. Peak numbers of bald eagles usually occur in late November and December, and again in early March. More than 140 have been observed at one time. Eagles are often found perched in cottonwoods along DeSoto Lake and the Missouri River when waterfowl are present.

DeSotos woods and prairies attract a variety of songbirds, with at least 240 species having been recorded on the refuge. During migration periods, shorebirds, warblers, gulls, herons, and egrets abound. White pelicans and cormorants usually stop in the area for several weeks during their migrations. Orioles, dickcissels, grasshopper sparrows and other sonbirds are common too. Some species such as turkeys, pheasants, blue jays, cardinals and woodpeckers are year-round residents. Bird List

Approximately 900 white-tailed deer make the refuge their home. Many local visitors drive the roads at dusk to see the deer grazing in the fields. Other mammals found in woods and fields include cottontail rabbits, raccoons, skunks, badgers, coyotes, opossums, and fox squirrels. Backwater areas of DeSoto Lake and several managed wetlands serve as habitat for beaver, muskrat, and mink. Foxes, weasels and other animals also occur on the refuge. Overall, about 30 species of mammals have actually been identified on DeSoto. Mammal List

There are two main communities of fish that occur on DeSoto those species that occur in DeSoto Lake, many of which are stocked for their sport-fishing qualities, and the naturally-occurring riverine species that are found in the Missouri River. DeSoto Lake contains a number of stocked game fish species, including largemouth and white bass, black and white crappie, channel and flathead catfish, bluegill, green sunfish, and walleye. Among the rough-fish whose populations have grown in recent years are carp, buffalofish, and gizzard shad. Gizzard shad and carp dominate the lake's biomass and are undoubtedly providing a considerable food source for predator fish. Fish List

Fourteen reptile species, including several snakes, turtles and one lizard, are residents of the refuge. At least ten species of amphibians, including a number of frogs, toads and one salamander, have been recorded on the refuge. Reptile/Amphib List

Scores of butterflies can be seen in woodlands and grasslands around the refuge. At least 60 species of butterflies have been recorded on the refuge. Dragonflies, damselflies, and a host of other facinating insects are also found at DeSoto. Butterfly List

Visitors to DeSoto will notice the nest boxes scattered around the refuge. These structures provide nesting sites for eastern bluebirds, trees swallows, wood ducks, screech owls and a few house wrens. In all, there are 48 bluebird/tree swallow boxes and 80 wood duck boxes. Each year the bluebird boxes are monitored weekly from mid-April until August, mostly by dedicated volunteers. Wood duck boxes are checked each fall to determine nesting success.