Elk Home Range - Rock Quarry - 2017-2022 [ds3032]

The project leads for the collection of this data were Josh Bush and Tom Batter. Elk (9 adult females, 6 adult males) from the Rock Quarry herd were captured and equipped with Lotek GPS collars (LifeCycle 800 GlobalStar, Lotek Wireless, Newmarket, Ontario, Canada), transmitting data from 2017-2022. The study area was almost entirely within the Cache Creek Elk Management Unit, stretching northwest into the Bear Valley Elk Management Unit, east of Clear Lake and south of Mendocino National Forest. The Rock Quarry herd contains short distance, elevation-based movements likely due to seasonal habitat conditions, but this herd does not migrate between traditional summer and winter seasonal ranges. Instead, the herd displays a residential pattern, slowly moving up or down elevational gradients. 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 at 13-hour intervals in the dataset. To improve the quality of the data set as per Bjrneraas 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 elk 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 analysis allowed for the mapping of the herds annual range based on a small sample. Brownian Bridge Movement Models (BBMMs; Sawyer et al. 2009) were constructed with GPS collar data from 14 elk in total, including 35 year-long sequences, location, date, time, and average location error as inputs in Migration Mapper to assess annual range. Annual range BBMMs were produced at a spatial resolution of 50 m using a sequential fix interval of less than 27 hours. Population-level annual range designations for this herd may expand with a larger sample, filling in some of the gaps between high-use annual range polygons in the map. Annual range is visualized as the 50th percentile contour (high use) and the 99th percentile contour of the year-round utilization distribution.

Disclaimer : The State makes no claims, promises, or guarantees about the accuracy, completeness, reliability, or adequacy of these data and expressly disclaims liability for errors and omissions in these data. No warranty of any kind, implied, expressed, or statutory, including but not limited to the warranties of non-infringement of third party rights, title, merchantability, fitness for a particular purpose, and freedom from computer virus, is given with respect to these data.

The user accepts sole responsibility for the correct interpretation of this report and the correct use of its accompanying dataset. Prior to using this dataset, please contact Josh Bush or Tom Batter to ensure correct interpretation of the data. The data is best interpreted at a scale of 1:100,000 or larger. Given the small sample size used to construct annual range utilization distributions from this herd, annual range for elk likely extends beyond the borders of what is considered high use annual range in our analysis, and likely does not represent the true extent of the home range for this herd. This analysis represents annual range from one elk population, and is one of a suite of datasets being developed for California's ungulate herds by CDFW.

CDFW makes no warranty of any kind regarding these data, express or implied. By downloading these datasets, the user understands that these data are subject to change at any time as new information becomes available. The user will not seek to hold the State or the Department liable under any circumstances for any damages with respect to any claim by the user or any third party on account of or arising from the use of data or maps. CDFW reserves the right to modify or replace these datasets without notification. No statement or dataset shall by itself be considered an official response from a state agency regarding impacts to wildlife resulting from a management action subject to the California Environmental Quality Act (CEQA).