Elk Home Range - Little Lake - 2022-2023 [ds3084]

The project lead for the collection of this data was Carrington Hilson. Elk (2 adult females) were captured and equipped with GPS collars (Lotek Iridium) transmitting data from 2022-2023. The Little Lake herd does not migrate between traditional summer and winter seasonal ranges. Therefore, annual home ranges were modeled using year-round data to demarcate high use areas in lieu of modeling the specific winter ranges commonly seen in other ungulate analyses in California. GPS locations were fixed between 1-7 hour intervals in the dataset. To improve the quality of the data set as per Bjørneraas et al. (2010), the GPS data were filtered prior to analysis to remove locations which were: i) further from either the previous point or subsequent point than an individual pronghorn is able to travel in the elapsed time, ii) forming spikes in the movement trajectory based on outgoing and incoming speeds and turning angles sharper than a predefined threshold , or iii) fixed in 2D space and visually assessed as a bad fix by the analyst. The methodology used for this migration analysis allowed for the mapping of the herd’s home range. Brownian bridge movement models (BBMMs; Sawyer et al. 2009) were constructed with GPS collar data from 2 elk, including 2 annual home range sequence, location, date, time, and average location error as inputs in Migration Mapper. BBMMs were produced at a spatial resolution of 50 m using a sequential fix interval of less than 27 hours. Home range is visualized as the 50th percentile contour (high use) and the 99th percentile contour of the year-round utilization distribution. Home range designations for this herd may expand with a larger sample.本数据集的采集项目负责人为卡林顿·希尔森（Carrington Hilson）。研究人员捕捉了2头成年雌性加拿大马鹿（Elk），并为其佩戴Lotek Iridium型号GPS项圈，该设备于2022至2023年间持续传输定位数据。 小湖种群（Little Lake herd）不存在传统夏、冬季活动范围间的迁徙行为，因此本研究采用全年采集的数据对年度家域进行建模，以划定高频使用区域，而非照搬加州其他有蹄类动物分析中常见的仅针对特定冬季活动范围建模的做法。 本数据集的GPS定位间隔为1至7小时。 为参照Bjørneraas等（2010）的方法提升数据集质量，研究人员在分析前对GPS数据进行滤波处理，剔除以下三类定位点：i）与前一或后一定位点的距离超出单只叉角羚在对应间隔时长内可移动的最大距离；ii）基于出射速度、入射速度及转角计算的运动轨迹出现尖峰，且转角超出预设阈值；iii）仅为二维空间定位，且经分析师目视评估为无效定位。 本次迁徙分析所采用的方法可实现该种群家域的制图。研究人员以2头加拿大马鹿的GPS项圈数据为基础构建布朗桥运动模型（Brownian bridge movement models, BBMMs；Sawyer等，2009），输入参数包含2组年度家域序列、定位点、日期、时间及平均定位误差，并在Migration Mapper软件中完成建模。 本次建模采用的布朗桥运动模型空间分辨率为50米，连续定位间隔小于27小时。 家域通过全年利用分布的50%分位数等高线（代表高频使用区域）与99%分位数等高线进行可视化展示。 该种群的家域划定结果可随样本量扩大进一步优化。