Migration Mapper

Project Overview

Migration Mapper™ is a free application designed for researchers, biologists, and managers, to analyze fine-scale GPS collar data collected from migratory ungulates.

Understanding and mapping where animals go is of utmost importance to wildlife conservation and management. Maps of animal movement are particularly important for efforts focused on migratory wildlife, as migratory animals rely on connected, seasonal habitats that span large landscapes.

In 2009, WMI researchers devised a method for analyzing GPS collar data collected from migratory ungulates (Sawyer et al. 2009). This methodology allows for identifying, mapping and prioritizing migration corridors. The methodology involves 1) a Brownian bridge movement analysis of GPS collar data collected for individual animals and 2) a prioritization analysis based on the number of animals migrating through specific areas. The issue with this methodology, however, is that it is computationally intensive, and requires coding and analysis skills that are beyond the reach of most biologists and managers. Therefore, WMI has invested in development of this application, which facilitates the technologically challenging analyses of animal movement and migration data.

HOW IT WORKS

Migration Mapper™ was not developed to be a ‘pull-the-handle-and-see’ program. Instead, Migration Mapper incorporates information from the user to identify migration corridors and winter ranges. Thus, you should expect to spend some time working with your data before Migration Mapper spits out a map of migration corridors or core winter ranges.

The workflow of Migration Mapper:

1. Import cleaned GPS collar data in ESRI Shapefile format;
2. Quantify whether individual animals are migratory, and if so, identify the date of the start and end of migration;
3. Calculate the utilization distribution of each individual’s migration movements and winter ranges using a Brownian Bridge Movement Analysis; and
4. Group animals into distinct populations and calculate population-level migration corridors and core winter ranges.

Migration Mapper provides the user with a number of outputs including:

1. shapefiles of high, medium, and low use migration corridors and stopover sites;
2. shapefiles of core, high, medium, and low use winter ranges;
3. a table of the start and end dates of annual spring and fall migration for every individual animal;
4. raster layers of individual and population-level utilization distributions of migratory corridors and winter ranges; and
5. shapefiles of the GPS locations used in the Brownian Bridge Movement Analysis.

project funders

Support for the development of Migration Mapper™ has come from Western Association of Fish and Wildlife Agencies, The Pew Charitable Trust, and The Knobloch Family Foundation. We especially thank Josh Gage (with Gage Cartographics LLC) and Jerod Merkle for writing the majority of code and leading the development of Migration Mapper.