Elk Home Range - Marble Mountain - 2006-2013 [ds2967]

The project leads for the collection of most of this data were Robert Schaefer and his colleagues at Rocky Mountain Elk Foundation. Elk (11 adult females, 3 adult males) from the Marble Mountain herd were captured and equipped with GPS collars (G2110B/D Advanced Telemetry Systems), transmitting data from 2006-2013. Two study areas were used to collect collar data from the same mountain range (Klamath Mountains), including within the Klamath National Forest and Marble Mountain Wilderness in the north and adjacent to the town of Cecilville in the Shasta-Trinity National Forest to the south. The Marble Mountain herd contains short distance, elevation-based migrants, but this herd generally does not migrate between traditional summer and winter seasonal ranges. Instead, much of the herd displays a somewhat nomadic migratory tendency, slowly moving up or down elevational gradients. Some individuals used higher elevation areas throughout the summer, though this pattern was not ubiquitous. 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 2-10 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 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 herd’s home range based on a small sample. Brownian Bridge Movement Models (BBMMs; Sawyer et al. 2009) were constructed with GPS collar data from 11 elk in total, including 12 sequences, location, date, time, and average location error as inputs in Migration Mapper to assess home range. Elk were separated into 3 distinct subherds (north - Ukonom; central - Wooley Creek subherd; south – South Fork subherd) due to non-overlapping data points among regions. North subherd had 2 individuals and 2 home range sequences, central had 2 elk and 3 home range sequences, and the south subherd had 7 individuals and 7 home range sequences. Home range BBMMs were produced at a spatial resolution of 50 m using a sequential fix interval of less than 27 hours. Population-level home range designations for this herd may expand with a larger sample, filling in some of the gaps between home range polygons in the map. Large water bodies were clipped from the final outputs. Home range is visualized as the 50th percentile contour (high use) and the 99th percentile contour of the year-round utilization distribution.