Mule Deer Migration Corridors - West Walker - 2017-2024 [ds3432]
Published by California Department of Fish and Wildlife
About this dataset
The project lead for the collection of this data was Tom Stephenson. Mule deer (171 adult females) from the West Walker herd were captured and equipped with store-onboard GPS collars (Lotek Pinnacle Pro and Vectronic Survey), transmitting data from 2017-2024. West Walker mule deer are largely traditional migrants, though some individuals are multi-range migrants, with a winter range within Antelope Valley in California and Nevada, stretching across State Route 395 into Slinkard Valley and Little Antelope Valley near Walker, California. In Spring, individuals move south and west into higher elevations in California using a variety of corridors; however, a concentrated movement corridor exists along the West Walker River, straddling State Route 395/State Route 108 and west of the Sweetwater Mountains, ending in the Sierra Nevada range. Most deer do not cross into Yosemite National Park, instead summering in Stanislaus and Humboldt-Toiyabe National Forest. Migrants vary in their movements from shorter (3 km) to longer (67 km) distances. GPS locations were fixed between 1-24 hour intervals in the dataset. The methodology used for this migration analysis allowed for the mapping of winter ranges and the identification and prioritization of migration corridors. Brownian Bridge Movement Models (BBMMs; Sawyer et al. 2009) were constructed with GPS collar data from 119 migrating deer, including 392 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 17.42 days and 27.99 km, respectively. Corridors and stopovers were prioritized based on the number of animals moving through a particular area. Products were best visualized with a fixed motion variance of 1000 at a spatial resolution of 50 m using a sequential fix interval of less than 27 hours. Winter range analyses were based on data from 126 individual deer and 328 wintering sequences. 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. Corridors are visualized based on deer use per cell, with greater than or equal to 1 deer, greater than or equal to 12 deer (10% of the sample), and greater than or equal to 24 deer (20% of the sample) representing migration corridors, moderate use 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. Winter range is visualized as the 50 th percentile contour of the winter range utilization distribution.