at a rate to maintain these numbers. We will continue to monitor them and protect them, but our research confirms they can survive only if they have suitable big river sand island habitat. Without suitable nesting habitat, we will have no least terns. And without new or restored habitat, their numbers will not grow.
Before leaving, I post signs around the island requesting people not to disturb the area during the tern breeding season, which runs from late May through August. As I drift away in the boat, the terns settle back onto their nests and resume feeding their chicks. It's a reassuring sight and seems to indicate a successful nesting season. We need that-and many more-if least terns are going to continue to inhabit Missouri's sand islands.
Our Endangered River
by Amy Salveter
Drawing its waters from a half million square miles, the Missouri River is the lifeblood of the central U.S. At one time, the "Big Muddy" sprawled across vast prairies, pulsating beyond its banks 300 feet during a single rise, shifting and depositing huge loads of nutrient-rich silt across the floodplain, sometimes relocating itself by a half mile in one year. These natural fluctuations created a rich variety of shallow- and deep-water breeding and feeding grounds-a complex web of life-that supported unique plants, fish, migrating birds and other animals.
Our efforts in this century to tame the unpredictable river have transformed the Missouri into a highly engineered, constrained system. Animals like the sicklefin and sturgeon chub-tiny fish near the beginning of the river's food chain-are suffering from dramatic modifications to the river.
The Big Muddy isn't as muddy as it used to be. Dams and rock-lined banks have reduced sediment in the river, lifting the muddy shroud that once helped hide the chubs from predators. The construction of 1,400 miles of levees has eliminated shallow, slow-moving side channels the fish need to feed, hide and reproduce.
The chubs' main food source-aquatic insects living among woody debris and vegetation-has become scarce. Because the river has been severed from its floodplain, sufficient trees and leaves no longer routinely wash into the river, and the destruction of side channels and islands has eliminated places where debris collects. Due to the channelization that supports barge traffic, today's Missouri flows twice as fast as the river Lewis and Clark knew, forcing the chubs to use more energy just to stay in one place.
The Missouri has been deemed one of the nation's "most endangered" rivers by American Rivers, a leading national river conservation organization. The group ranks rivers throughout the U.S. that are threatened by development, dams, pollution and other problems. The sicklefin and sturgeon chub are not the only fish species suffering from the impacts of habitat degradation. Pallid sturgeon, paddlefish, sauger, blue sucker, flathead catfish, longnose gar, blue catfish, flathead chub, speckled chub and silver chub are other species struggling to survive in the radically altered-and endangered-Missouri River.
To learn more, write American Rivers, 1025 Vermont Ave. NW, Suite 720, Washington D.C., 20005; or visit their website.