Data on black-tailed prairie dog body mass, distance to nearest male and female black-footed ferret, distance to nearest American badger, and reencounter from early to late summer 2005 (Montana) and 2009 (South Dakota)

Our study was conducted in 2005 on 3 colonies of black-tailed prairie dogs on lands in Phillips County, Montana administered by the Bureau of Land Management and in 2009 on a colony of black-tailed prairie dogs on Buffalo Gap National Grassland, Pennington County, South Dakota managed by U.S. Forest Service. We live-trapped black-tailed prairie dogs in daylight with wire mesh traps and marked their ears with numbered tags for individual identification. We weighed each individual to the nearest gram and collected Universal Transverse Mercator coordinates of their trapping locations over time. In Montana, trapping began on 15 June 2005 and ended on 1 October 2005. In South Dakota, trapping was conducted during 7 June through 7 October 2009. In both states, trapping was split into two sessions, early summer (June-July) and late summer (August-early October). An individual prairie dog was classified as encountered for the early summer session if it was detected at any time during that session and reencountered if it was detected one or more times during the late summer session. For each site, we calculated the center of activity for individual prairie dog capture locations as the mean of X-coordinates and the mean of Y-coordinates. We located adult black-footed ferrets and adult American badgers via spotlighting on nearly consecutive nights each field season. Ferrets of known age and sex were individually identifiable via passive integrated transponders. In South Dakota, but not Montana, locations of adult American badgers were recorded; adult badgers of unknown sex were not individually identifiable. We transformed prairie dog body mass (from initial capture in each state) into a binomial, categorizing prairie dogs of ≥ 600 grams at first capture as large and those of < 600 grams as small. We calculated the Euclidean distance separating each prairie dog center of activity from the closest location for any adult female ferret, any adult male ferret, and any badger. Given more intense monitoring in South Dakota for prairie dogs and ferrets alike, we were able to define individual prairie dogs as spatially "near" ferrets or badgers if their center of activity was ≤ 20 meters from the nearest adult female, male ferret, or badger spotlight locations. Data collection in Montana was less intense and the prairie dogs and ferrets were more spatially dispersed; thus, we extended the definition of “near” to ≤ 50 meters for Montana. Prairie dogs with activity centers beyond these distance cutoffs were classified as "far" from the nearest adult female, male ferret, or badger. The first dataset (Prey Selection Data.csv) includes variables for state, prairie dog reencounter from early to late summer, prairie dog body size, distance to adult female ferret, distance to adult male ferret, and distance to badger. The second dataset (Juvenile Prairie Dog Mass South Dakota Data.csv) includes data on juvenile prairie dog body mass in South Dakota, and includes variables for date of capture, state, prairie dog age, and the juvenile prairie dog's body mass in grams at capture. Only the mass measurements for juveniles in South Dakota were analyzed in the Larger Work manuscript cited herein. Funding for this study was provided by the U.S. Geological Survey Fort Collins Science Center internally and through the collaborative USGS/U.S. Fish and Wildlife Service Species Survival Program.

本研究于2005年在蒙大拿州菲利普斯县由土地管理局（Bureau of Land Management）管理的土地上的3个黑尾土拨鼠（black-tailed prairie dog）种群开展，并于2009年在南达科他州彭宁顿县布法罗加普国家草原（Buffalo Gap National Grassland）由美国林务局（U.S. Forest Service）管理的1个黑尾土拨鼠种群开展。本研究采用日间金属丝网陷阱对黑尾土拨鼠进行活捕，通过带编号的耳标对个体进行标记以实现个体识别；称量每只个体的体重，精确至克，并记录随时间变化的捕获地点的通用横轴墨卡托（Universal Transverse Mercator）坐标。
蒙大拿州的捕获工作始于2005年6月15日，结束于2005年10月1日；南达科他州的捕获工作则于2009年6月7日至10月7日期间开展。两个州的捕获均分为两个时段：初夏（6-7月）与夏末（8月至10月初）。若某只黑尾土拨鼠在初夏时段的任意时间被检测到，则归类为初次遇见个体；若在夏末时段被检测到1次及以上，则归类为再次遇见个体。针对每个研究位点，以个体捕获地点的X坐标均值与Y坐标均值计算其活动中心。
在每个野外季中，通过夜间聚光灯追踪法定位成年黑足雪貂和成年美洲獾。已知年龄与性别的雪貂可通过被动集成应答器（passive integrated transponders）实现个体识别。仅在南达科他州记录了成年美洲獾的位置，且未知性别的成年獾无法实现个体识别。
本研究将两个州黑尾土拨鼠首次捕获时的体重转换为二分类变量：首次捕获时体重≥600克的个体划分为大型，体重<600克的个体划分为小型。计算每只黑尾土拨鼠的活动中心与最近的成年雌性雪貂、成年雄性雪貂以及美洲獾位置之间的欧氏距离（Euclidean distance）。
鉴于南达科他州针对黑尾土拨鼠与雪貂的监测强度更高，因此将活动中心距离最近的成年雌性、雄性雪貂或美洲獾聚光灯追踪位置≤20米的个体，定义为与这些捕食者空间邻近。而蒙大拿州的数据收集强度较低，且土拨鼠与雪貂的空间分布更分散，因此将该阈值放宽至≤50米。活动中心超出上述距离阈值的黑尾土拨鼠则被归类为远离最近的成年雌性、雄性雪貂或美洲獾。
本研究包含两个数据集：第一个数据集（"Prey Selection Data.csv"）包含以下变量：州、黑尾土拨鼠从初夏到夏末的再次遇见情况、黑尾土拨鼠体型、与成年雌性雪貂的距离、与成年雄性雪貂的距离以及与美洲獾的距离。第二个数据集（"Juvenile Prairie Dog Mass South Dakota Data.csv"）包含南达科他州幼年黑尾土拨鼠的体重数据，变量包括捕获日期、州、黑尾土拨鼠年龄以及捕获时幼年黑尾土拨鼠的体重（克）。本文引用的相关研究手稿仅对南达科他州幼年个体的体重测量数据进行了分析。
本研究的资助由美国地质调查局柯林斯堡科学中心内部提供，并通过美国地质调查局/美国鱼类及野生动物管理局物种生存计划的合作项目获得。