Elk Home Range - Laytonville - 2022-2023 [ds3083]

The project lead for the collection of this data was Carrington Hilson. Elk (1 adult female) were captured and equipped with GPS collars (Lotek Iridium) transmitting data from 2022-2023. The Laytonville 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 1 elk, including 1 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.本数据集采集工作的项目负责人为卡林顿·希尔森（Carrington Hilson）。研究团队捕获1头成年雌性马鹿（Elk），为其佩戴Lotek铱星GPS项圈（Lotek Iridium）以采集数据，数据采集时段为2022年至2023年。莱顿维尔种群并未在传统的夏季与冬季活动范围之间进行迁徙。因此，本研究采用全年监测数据对年度家域进行建模，以此划定高频使用区域，而非如加州其他有蹄类动物分析那般，针对特定冬季活动范围开展建模工作。本数据集的GPS定位间隔为1至7小时。为提升数据集质量，参照比约纳拉斯等（Bjørneraas et al., 2010）的研究方法，分析前对GPS数据进行了滤波处理，以剔除以下三类定位点：i）该定位点与前一定位点或后一定位点的间距，超出了单只叉角羚在该间隔时长内可移动的最大距离；ii）基于出射速度、入射速度及转角形成运动轨迹尖峰，且转角超出预设阈值；iii）仅采用二维定位且经分析人员目视评估为无效定位的点。本次迁徙分析所采用的方法可实现该种群家域的可视化制图。研究以1头马鹿的GPS项圈数据为基础，构建了布朗桥运动模型（Brownian Bridge Movement Models, BBMMs；Sawyer et al., 2009），并将1组年度家域序列、定位坐标、日期、时间及平均定位误差作为输入参数导入Migration Mapper中运行。本次构建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%百分位等值线（高频使用区）与99%百分位等值线进行可视化呈现。该种群的家域划定范围或可随着样本量增加进一步扩大。