Platte River Management Joint Study Final Report

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46 sandhill crane habitat suitability model (Armbruster and Farmer 1981) designed to evaluate the composition, distribution, and spatial relation of cover types, disturbance factors, and potential roosting areas in the central Platte River area occupied by sandhill cranes. A simulation model developed by the Bureau,(Latka and Yahnke 1986) was designed to predict the distribution of roosting sandhill cranes in the channels of the Platte River based on microhabitat features of flow given certain macrohabitat constraints. Currier.and Eisel (1984) evaluated the impact of flow level on sandhill crane and whooping crane roosting habitat. Currier and Eisel's model evaluated roosting habitat suitability based on wetted width criteria and was developed through analysis of aerial. photographs taken at different flows. Currier et al. (1985) used a Geographic Information System (GIS) to determine the availability of optimum whooping crane roost sites in the Big Bend of the Platte River. The GIS model does not have a-flow component. A problem common to most modeling efforts, and especially those involving endangered species, is the paucity of data beyond the minimum needed to generate data points. Most of the models examined at the beginning of the Biology Workgroup's review process were not used.because they either did not apply to the Platte River, or to the endangered species involved, or the models did not evaluate habitat vs. flow relationships. The. Habitat Suitability Index (HSI) modeling approach designed by the Fish and Wildlife Service enables the development o,f suitability curves for various habitat parameters which evaluate a particular habitat component on a scale of 0.0 to 1.0. The habitat models examined initially by the Workgroup did not provide a means-for assigning a numerical vaZue to a habitat character, or a mechanism for tying together most aspects of the habitat characters portrayed. A summary analysis of the earlier available models led the Biology Workgroup to-conclude that more applicable models should be developed to•address the habitat and management needs of endangered species occupying Platte River habitats. State-of- the-art technology under development by the National Ecology Research Center in Fort Colli.ns, Colorado, p.resented the possibility of.assessing incremental changes in quantity and quality of the instream habitat at incremental flows (Instream Flow Incremental Methodology). Field data collected by the Bureau and others enabled the application of the Instream Flow Incremental Methodology. 'The.Biology tidorkgroup recommended that models be developed that would address habitat needs of each of the endangered species occupying the Platte River. The models would be specific to certain reaches of the river and would quantify habitat vs. flow relationships for each species at the time of the year when the species was present.on the Platte River. .