In western Iowa, the Desoto National Wildlife Refuge wetlands become a temporary home for a variety of waterfowl and shorebirds in the spring and fall. A variety of birds depend on the aquatic and wetland habitats including mallards, Canada geese and pelicans. This migration of snow geese on the Missouri River flyway is captured at peak migration when up to 500,000 geese are over the area at any given time.