The raucous honks of migrating geese herald the spring in south-central Nebraska. Overhead, long skeins of waterfowl weave intricate patterns in the sky. Mallards, northern pintails, and other ducks paddle by the hundreds and thousands in shallow wetlands. Here and there, cornfields seem blanketed in white, where tens of thousands of snow geese waddle through rows of stubble to feed on waste grain. When they take to the air, the flurry of wings resembles a small blizzard.
Credit: T. Horst
This is the Rainwater Basin, a landscape of shallow playa wetlands scattered amid flat or gently rolling loess plains. The Rainwater Basin lies at the narrowest portion of the Central Flyway migration route. A 160-mile-wide region gathers up the millions of migrating ducks, geese, shorebirds and other water birds that have wintered along the Gulf Coast, across Texas and Mexico, and farther south. From late February through March each year, ducks and geese stop over on the way to their breeding grounds; shorebirds follow from mid-April to mid-May. To humans, it’s a fascinating wildlife spectacle. To birds, this region is a vital resource – a linchpin in their annual life cycle.
Northbound birds stopping in the Rainwater Basin must accumulate and store energy in the form of fat reserves that help them complete migration and survive after their arrival on the breeding grounds. For many species, nesting success is directly affected by the birds’ ability to find adequate nutrition during migration, and is therefore directly tied to their stopover in the Rainwater Basin.
Waste grain in the Rainwater Basin’s corn fields is an ample source of calories; however, waterfowl also need nutrients provided by wetland plants; shorebirds and other birds rely on invertebrates found in healthy wetlands and uplands.
Before European-American settlement, this region contained some 11,000 wetlands ranging in size from over 1,000 acres to less than one acre, and totaling over 200,000 acres. These wetlands filled with runoff from snowmelt, springtime rains, and intense summer storms. By mid- to late-summer, all but the largest wetlands were usually dry. Growth and succession of wetland plant communities were kept in check by herds of grazing bison, elk, and pronghorns, and by fires that swept the prairies every few years.
Until the middle of the twentieth century, Rainwater Basin wetlands were integrated and productive elements in diversified farm operations, serving as pastures for cattle and other livestock. Domesticated grazers emulated the effects of bison and other wild ungulates, helping to keep wetland vegetation in the early successional state that provided suitable migration habitat for waterfowl, shorebirds, and other wetland-dependent birds.
Economic forces and technical changes led to an expansion of row crops at the expense of diversified farms. Many wetlands were drained for cultivation, often with the help of federal farm programs. Wetlands that were too large to drain, but were no longer grazed, became choked with late-succession plants, including trees.
By the early 1980s, only 10% of the Rainwater Basin’s wetlands remained, covering little more than one-fifth of the original acreage. Irrigation pits, ditches, and other water-diverting modifications had degraded the function of virtually every remaining wetland in the region, on both public and private land.
When it began operations in 1992, the Rainwater Basin Joint Venture’s primary objective was to halt and reverse the loss of Rainwater Basin wetlands and ensure adequate habitat for the migrating birds that continue to depend on this region.