Pronghorn Migration Corridors - Bodie-Wassuk - 2014-2016 [ds3100]

The project leads for the collection of this data were Tim Taylor and Tom Stephenson. Pronghorn (20 adult females) were captured and equipped with GPS collars (Televilt Tellus Iridium, Sweden) transmitting data from 2014-2016. The Bodie-Wassuk herd contains migrants, but this herd does not migrate between traditional summer and winter seasonal ranges. Instead, much of the herd displays a somewhat nomadic migratory tendency, moving between the Bodie Hills east of U.S. Highway 395 in California to a basin west of the Wassuk Range between Aurora Crater and Corey Peak in Nevada. A few collared individuals moved as far north as the Gray Hills, staying west of the Wassuk Range, with one individual moving as far south as the Alkali Valley. Therefore, annual 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 4-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 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 herds annual range and the identification and prioritization of migration corridors. Brownian Bridge Movement Models (BBMMs; Sawyer et al. 2009) were constructed with GPS collar data from 18 migrating pronghorn, including 102 migration sequences, location, date, time, and average location error as inputs in Migration Mapper. The average migration time and average migration distance for pronghorn was 4.85 days and 17.44 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 and a fixed motion variance rate of 1000. Annual range analyses were based on data from 17 pronghorn and 21 year-round sequences using a fixed motion variance of 1000. Annual range designations for this herd may expand with a larger sample, filling in some of the gaps between annual range polygons in the map.

Corridors are visualized based on pronghorn use per cell, with less than or equal to1 pronghorn and less than or equal to 4 pronghorn (20 percent of the sample) representing migration corridors and high use corridors, respectively. 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. Annual range is visualized as the 50 th percentile contour of the annual 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 Tom Stephenson 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 and migration corridors from this population, the annual range of these pronghorn 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 annual range for this population. Moreover, our sample only represents a fraction of the possible population of pronghorn migrating in this area; therefore, other corridors may have gone undetected in our analysis. This analysis represents migration corridors, stopovers, and annual range from one pronghorn population, and is one of a suite of datasets being developed for Californias 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).