Platte River Management Joint Study Final Report

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45 Ultimately, the model of black-shouldered kites in south Texas was based on information primarily from northern California (extreme northern limit of the species range; AOU 1983) and from El Salvador in Central America. Although the model contains many biologically valid assumptions about the kite in south Texas, its accuracy would have been improved considerably had geographically specific information been available and included in the south Texas model. The same concept is applicable to management of endangered species using the Platte River ecosystem in Nebraska. Although the whooping crane, for example, occupies palustrine wetlands for nocturnal roosting habitat over much -of its 2400 mile-long migration corridor (Howe 1987)., when bccupying the Platte River, whooping cranes use riverine habitats. Data on-habitat characteristics in riverine;sy.stems on the Great Plains in general, and in the Platte River specifically, greatly increases the accuracy of the model. The Biology Workgroup's Platte River-specific model provides a firm theoretical base for making management decisions. _ In the development of its habitat models, the Biology Workgroup had to make assumptions to apply the data. The general assumptions used in the species models were: (1) the future conditions to be modeled were available at the time use data were collected, (2) in some of the model effbrts, observed habitat use reflected the needs of the species, (3) current habitat __. conditions on the Platte River included optimum conditions, (4) the habitat variables incorporated in the model were independent, and (5) that all habitat factors are of equal value. 2. Describe and evaluate previous modelinQ efforts for endanQered and threatened species on the Platte River. Mo,dels available when the Biology Workgroup was formed were generally inadequate to describe habitats occupied by endangered and threatened species on the Platte River. The principal inadequacy of each model examined was the lack of speciticity in addressing habitat needs related to endangered species in alluvial systems. For instance, the only least tern model available (Carreker 1985) was developed for application throughout the North American breeding.range of the species, including all three subspecies (two of which are.coastal). Because ot the broad applicability of the Carreker model, habitat needs applicable to the Platte River system were necessarily- given only rudimentary-coverage-in that model. At the same time, no models existed for the piping plover anywhere in its North . American breeding range. Among the habitat models examined during the review process for applicability to whooping crane habitat process was a draft