Mule Deer Migration Corridors - Bucks Mountain-Mooretown - 2018-2020 [ds2972]

The project leads for the collection of this data were Sara Holm and Julie Garcia. Mule deer (4 adult females) from the Bucks Mountain-Mooretown herd were captured and equipped with Lotek Iridium Track MGPS collars, transmitting data from 2018-2020. GPS fixes were between 12-13 hours. The Bucks Mountain-Mooretown herd migrates from winter ranges in the American Valley, Crescent Hill, and various high elevation locations of the Sierra Nevada range east and south to even higher altitude terrain in Plumas National Forest. 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 deer 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 winter ranges and the identification of migration corridors. Brownian Bridge Movement Models (BBMMs; Sawyer et al. 2009) were constructed with GPS collar data from 4 migrating deer, including 11 migration sequences, location, date, time, and average location error as inputs in Migration Mapper. The average migration time and average migration distance for deer was 13.09 days and 27.77 km, respectively. Corridors and stopovers were prioritized based on the number of animals moving through a particular area. BBMMs were produced at a spatial resolution of 50 m using a sequential fix interval of less than 27 hours. Due to the majority of BBMMs producing variance rates greater than 8000, a fixed motion variance of 1000 was set per migration sequence. Winter range analyses were based on data from 4 individual deer and 6 wintering sequences using a fixed motion variance of 1000. Winter range designations for this herd may expand with a larger sample, filling in some of the gaps between winter range polygons in the map. This collar project was not specifically designed to pinpoint precise migration routes or winter range designations, hence the low sample size. Additional migration routes and winter range areas likely exist beyond what was modeled in our output.

Corridor tiers (low, medium, high) could not be computed with such a small dataset. Therefore, all corridors were given the same weight and designation in this analysis. Stopovers were calculated as the top 10 percent of the population level utilization distribution during migrations and can be interpreted as high use areas. Stopover polygon areas less than 20,000 m 2 were removed, but remaining small stopovers may be interpreted as short-term resting sites, likely based on a small concentration of points from an individual animal. Winter range is visualized as the 50 th percentile contour of the winter range utilization distribution.

License : This work is licensed under Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ ). Using the citation standards recommended for BIOS datasets ( https://www.wildlife.ca.gov/Data/BIOS/Citing-BIOS ) satisfies the attribution requirements of this license.

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 Julie Garcia, Sara Holm, or Stacy Anderson 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 winter range utilization distributions and migration corridors from this herd, winter range for deer likely extends beyond the borders of what is considered winter range in our analysis, and likely does not represent the true extent of the winter range for this herd. Moreover, our sample only represents a small fraction of the possible population of deer migrating in this area; therefore, other corridors may have gone undetected in our analysis. This analysis represents migration corridors, stopovers, and winter range from one deer herd, one study, 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).