Four male ringtails (Bassariscus astutus) were radio-collared in the Geysers-Calistoga Known Geothermal Resource Area, Sonoma County, California, and monitored from April through June 1981. Three hundred and forty-one locations of the animals were obtained by telemetry and used to determine home range and habitat utilization patterns. The ringtails occupied exclusive but adjacent home ranges, ranging from 49 to 338 hectares (x = 221 hectares). Ringtail preference for each of 10 vegetation types in the area was analyzed by comparing the percentage of area of each type in the home ranges with the percentage of telemetry locations obtained in each type. Riparian woodland was the most preferred type while serpentine chaparral was the most avoided type. Riparian woodland and mixed evergreen forest types were the only vegetation types that occurred in all 4 home ranges. Forty-one ringtail scats were analyzed to determine spring food habitats. Mammals, birds, insects, and vegetable matter constituted 56.1% 21.4%, 5.5% and 17.0% of the aggregate volume of the scats, respectively. Simple statistical analyses of telemetry locations in relation to the location of geothermal development did not reveal any direct impacts on habitat utilization from geothermal development. The effect of development is veiled by the complex interrelation of topography, vegetation type, and location of development, and will require more extensive ecological study. However, it is likely that the lack of extensive riparian habitat in the area was more important in limiting the Geysers ringtail population than the current level of geothermal energy development.
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