Organizing for Endangered and Threatened Species Habitat Draft

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channel area (Figure 4). According to land survey maps, channel widths in 1965 were 21 to 73 percent of the 1865 widths recorded. Because of controlled releases from reservoirs upstream, there is less variability in over-all river flows than there were historically. The Pathfinder Reservoir, completed in 1909, was the first major impoundment on the North Platte, followed by Guernsey (completed in 1927), Alcova (1938), Seminole (1939), McConaughy (1941) and Glendo (1957). These reservoirs dropped peak flows on the North Platte by 86% (Currier, Lingle, and Walker 1985: 96). This change has resulted in a net loss of water-filled channel and an associated increase in vegetated river-banks. This, in turn, has meant loss of roosting, nesting and feeding habitat that comes with loss of ineanders and grasslands-wetlands near the main river channel. With 80% of the North American crane flock dependent on the central Platte, any further loss of habitat would be most threatening. Reduction of available habitat for all the species of birds that traditionally made use of the Platte basin creates two forms of hardship: 1) competition for the limited food supply; and 2) crowded conditions exacerbates disease transmission. Avian cholera and tuberculosis brought in by snow geese poses a threat to the health of many birds and most particularly cranes. Crowding contributes to disease transmission. As wetlands have been drained and woodlands grown up along the banks, crane habitat has shrunk from hundreds of miles of prime river habitat to less than 70 miles in the Kersey and Grand Island area. Here cranes and other bird crowd dangerously close in the few good habitat reaches that remain (Currier, Lingle, and Walker 1985: 18). ? Caloric requirements for migration used to be met by starchy tubers from a variety of ? aquatic plants, worms, snails, snail shells and insects in the floodplain. Now, within 8 miles of • the river, 96% of the cranes' diet is found in waste corn. The remaining 4% is the critical invertebrate component which provides protein and calcium for egg production. What little ? habitat is left for spring and autumn stopovers is as important as the suinmer and winter ? destinations themselves and not only for cranes, but also for snow geese, mergansers, mallards, ? teal, pintail ducks, and bald eagles. The interior least tern is a small bird approximately nine inches in body and twenty inches in wingspan. In recent decades, this species has been found on only a fraction of its former habitat that, early in the twentieth century, had stretched from Texas to Montana and &om the front range of eastern Colorado and New Mexico to Indiana. The species was listed as threatened in 1985 and recent estimates place its population at about 4,800 W.S. Fish & Wildlife Service 1990). Interior least terns nest in colonies where there is little or no vegetation, in shallow inconspicuous depressions in open sandy areas. In Nebraska, they are found on sandbars of the Missouri, the Loup, the Nebraska, and the Platte rivers, on the beaches of Lake McConaughy, and on shores of sandpits created by human extraction of gravel. Piping Plovers are similar to least terns in that they nest in the same areas and compete for the same resources. This species was listed under the Endangered Species Act as threatened in 1985. A 1991 census estimated its population in both Canada and the U.S. to be about 2440 breeding pairs. The population is distributed from southeastern Alberta to northwestern Minnesota and along prairie rivers and reservoirs to southeastern Colorado. About 10% were estimated to breed primarily along rivers and 90% nested around lakes and ponds (U.S. Fish & 12