Species Recovery Objectives for Four Target Species in the Central and Lower Platte River

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the data available, including the number of crane sightings as well as the number of cranes. B.6. Platte River Objectives Although it is recommended that 100 percent of the recovered AWP should be managed for in the central Platte River area, it is recognized that birds pass over the upper Platte River now, and some provisions for their habitat stopover needs should not be excluded. Suitable riverine stopover habitat in the upper Platte River, as well as the central Platte River, may be particularly important during drought cycles where such areas may be the only ones available in that part of Nebraska. One or more habitat developments could be provided for whooping cranes west of the central Platte River although the feasibility of such habitat work may be questionable. In areas where river channel roost habitat is not restorable, it may be beneficial to manage roosting habitat in restored wetlands off the river. Such concepts should be studied and analyzed thoroughly prior to making decisions. Nevertheless, the priority for whooping crane habitat restoration and management on the Platte River should focus on the central Platte River. This is because the majority of whooping crane stopovers occur on the central Platte River and that is where habitat management can be most beneficial (river channel, wet meadow, and flow management). If it is determined at a future time that some habitat development and management is feasible in the upper Platte River area, a 90:10 split in terms of the proportion of whooping crane use or stopovers could be selected as a revised objective at that time. That is, management could occur for 90 percent of whooping crane stopovers on the central Platte River and for 10 percent of stopovers west of the central Platte River. The rationale for the 90:10 split is that if 10 habitat complexes are developed along bridge segments from Lexington to Chapman, as currently proposed, and if at least one habitat development occurred west of the central Platte River, then roughly 90 percent of new recovered suitable habitat would be available in the central Platte River and 10 percent would be available west of the central Platte River. Again, this report stresses that existing suitable habitat should remain on the central Platte River exclusive of future restored and managed habitat. B.7. Managing for the Population Objective B.7.1. Population Ratios Population ratios are difficult to establish and monitor because the detection of bird stopovers varies with effort and the efficiency of detecting stopovers is really not known. Recognizing this problem, this report recommends that population ratios provided by Dr. Doug Johnson be used as indices of whooping crane use of the Platte River and to estimate the potential changes in use. Separate ratios could be selected for fall and spring populations. For the fall, the peak winter population at Aransas NWR (typically in December) should be used. For the spring, the number of birds departing Aransas should be used. The ratios should be calculated using "confirmed" and "probable" sightings on the Platte River separately and possibly combine them, if beneficial. Combining "confirmed" and 041