Whooping Crane Migrational Habitat Use Draft (2)

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so there can be no increase in use until the available habitat increases, cranes prefer other stopover habitats, or stopover locations are chosen randomly. With continued monitoring of the index of use and with reference data on use at other stopover habitats, these data will be able to provide a better understanding of patterns of whooping crane use in the study area. Activity Monitoring During the spring and fall migrations, crane groups were observed spending more time during the day feeding in the study area than performing any other activity. Resting, alert, and preening activities were also occasionally observed. Courtship and defensive activities were rare and were observed only in the spring. These observations are consistent with expected diurnal activities during migration; that is, birds will need to feed often and they tend to conduct courtship activities during the spring season. No unique activities were documented during the 2001-2006 monitoring period. This summary represents diurnal use during the period of observation by the field crews. Observations were made throughout the day in upland and channel habitats, but the data was combined to calculate the estimates presented here. As more data is collected, it will be possible to make estimates by habitat and subsets of the day. Habitat Selection - Land use/land cover The spatial composition of vegetation types and land use components at whooping crane group use locations influenced habitat selection. Habitat selection models of land cover for both in- channel and uplands suggested that use of the study area by whooping cranes was highly influenced by the amount of open water and agricultural lands. Habitat selection models that described use within the study area contained the variables percent of wetted channel, percent of open water, and percent of agriculture. That is, whooping crane use was higher in areas with high proportions of wetted channel, open water, and agriculture compared to other land cover types, irrespective of whether the use location was in the channel or out of the channel. Habitat selection models specific to in-channel use contained these same variables, as well as the distance from transportation features (i.e. roads and bridges) and shrub and forest. Models for local selection were consistent with these results. The survey results from 2001-2006 support the assertion that whooping cranes utilize areas of wetted channels, open water, and agriculture that are away from potential disturbances (i.e., roads) and trees/shrubs while on the Platte River. It appears, however, that there is a limit to the influence some of these land cover variables have on habitat selection For example, the influence of the shrub/forest land cover diminishes as distances approach 200 meters (Figure 20). There was no difference in the biological interpretation between land use/ cover models developed for the systematic observations and the combined systematic and opportunistic observations. Model selection for the combined dataset led to slightly different final models, though there was no biological difference between the model parameterization and the interpretation of the common effects in the models. 16