Rainwater Basin
The raucous honking of Canada geese heralds the spring in south-central Nebraska. Overhead, long skeins of migrating waterfowl weave intricate patterns in the sky. In the distance a cornfield looks blanketed in white, where tens of thousands of snow geese waddle through rows of stubble to feast on waste grain. When they take to the air, the flurry of wings resembles a small blizzard.This is the Rainwater Basin, a landscape that was formed at the end of the last ice age, when glacial winds carved thousands of shallow, bowl-shaped depressions. Gradually, clay particles filtered down and lined each depression with a nearly-impermeable pan, so that, for some twenty thousand springs, the snow melted and spring rains filled the basins to create a seasonal haven for migrating birds.
Lifelong Nebraskans, long accustomed to the sound and sight of this natural spectacle, may take it for granted, but the Rainwater Basin waterfowl migration has few rivals anywhere on earth.
The Rainwater Basin area is the narrowest portion of the migration route known as the Central Flyway. In the spring, water birds that have wintered on the Gulf Coast and across Texas, Mexico and points south funnel into a 150-mile-wide area that contains several hundred wetlands covering some 21,000 acres.
From mid-February to mid-March, many millions of waterfowl will use the wetlands and uplands of the Rainwater Basin Region of Nebraska for resting, feeding and pair bond formation. The numbers are almost unfathomable: three to six million snow geese, four million mallards, 900,000 white-fronted geese, 900,000 pintails, plus millions of other migrating birds, including Canada geese, shorebirds and cranes.
As migratory habitat, the Rainwater Basins play a brief but crucial role in the life cycles of many species of birds. They are also home to numerous birds and wildlife throughout the year, including blue-winged teal, mallards, kildeer, American avocets, black-crowned night herons, northern harriers, and yellow-headed blackbirds.
For humans, the benefits of wetlands include outdoor recreation and flood control. Research studies in the Rainwater Basin are being developed to quantify the basins’ contribution to water quality and groundwater recharge.