Linkage Mapper is a GIS tool designed to support regional wildlife habitat connectivity analyses. It consists of several Python scripts, packaged as an ArcGIS toolbox, that automate mapping of wildlife habitat corridors. We developed these scripts for the Washington Wildlife Habitat Connectivity Working Group’s (WHCWG) 2010 statewide connectivity analysis, and are making them public for use in other wildlife connectivity assessments.

Linkage Mapper uses GIS maps of core habitat areas and resistances to identify and map linkages between core areas. Each cell in a resistance map is attributed with a value reflecting the energetic cost, difficulty, or mortality risk of moving across that cell. Resistance values are typically determined by cell characteristics, such as land cover or housing density, combined with species-specific landscape resistance models. As animals move away from specific core areas, cost-weighted distance analyses produce maps of total movement resistance accumulated.

The scripts use ArcGIS and Numpy (numerical Python) functions to identify adjacent (neighboring) core areas and create maps of least-cost corridors between them. The scripts then normalize and mosaic the individual corridor maps to create a single composite corridor map. The result shows the relative value of each grid cell in providing connectivity between core areas, allowing users to identify which routes encounter more or fewer features that facilitate or impede movement between core areas. More details on the models implemented by the scripts are given in Chapter 2 and Appendix D in WHCWG (2010).

The code runs fastest in ArcGIS 10, but is also tested for ArcGIS 9.3.

Please note: whatever tool you use, connectivity modeling involves a great deal of research, data compilation, GIS analyses, and careful interpretation of results. Defining areas to connect, parameterizing resistance models, and other modeling decisions you will need to make are not trivial. Before diving in, we strongly recommend that users first acquaint themselves with the process and challenges of connectivity modeling by consulting published resources. Good places to start include an overview of habitat and corridor modeling on the Corridor Designer website and references listed in the Linkage Mapper user guide.

Linkage Mapper was developed with support from the Great Northern Landscape Conservation Cooperative and the Wildlife Conservation Society's Wildlife Action Opportunities Fund. We are enhancing Linkage Mapper with support from the North Pacific Landscape Conservation Cooperative.

Linkage Mapper is in active development. Please join the Linkage Mapper User Group for updates on new releases.