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attached map). The scattered nature of the towns within the study area and access <br /> problems associated with fence lines and topography precluded the field observers <br /> from spotlighting the remaining 21 acres within the time constraints specified by <br /> USFWS guidelines. Areas not surveyed were primarily small isolated towns or portions <br /> of towns where initial ocular estimates indicated relatively low prairie dog burrow <br /> densities. <br /> Specific techniques used for the night spotlighting surveys followed USFWS (1986) <br /> guidelines, except that two nighttime survey periods were employed instead of three. <br /> Recent evidence obtained by the USFWS indicate that the mid-nighttime hours are of <br /> limited utility for locating ferrets by spotlighting and that the hours after sunset and <br /> before sunrise are, by far, the most productive for locating ferrets (Biggins, USFWS, <br /> pers. comm. 1987). Each prairie dog town was surveyed by spotlighting during the <br /> hours between dusk and dawn for the three consecutive nights. For each night <br /> spotlight survey period, the towns were searched during two different time periods (3 <br /> hours after dusk and 3 hours before sunrise). Spotlight surveys were begun at opposite <br /> ends of the study area on each successive night to maximize the potential of the survey <br /> route to overlap the ferret's nighttime activity period for a particular area. <br /> For each town or section of town surveyed, a spotlight route or observation point <br /> was chosen,mapped on an aerial photograph of the study area, and marked with stakes <br /> or flagging, where necessary, during a daytime period prior to the survey. In most <br /> instances,fences, farm houses, roads, and other prominent landmarks were sufficient <br /> to locate survey routes or observation points and actual route marking was not <br /> necessary. Routes and observation points were chosen to avoid obstacles, take <br /> advantage of topography, and provide the maximum amount of unobscured visual <br /> coverage of the the town surveyed. Where small towns or relatively narrow, linear <br /> 4 <br />