Gnarly Landscape Utilities is an ArcGIS toolbox designed to support some of the less-glamorous tasks involved with connectivity modeling. It includes tools for creating resistance and habitat layers and core area mapping. The core area mapping functionality was formerly packaged as the HCA Toolkit.

We created the tools to support connectivity analyses by the Washington Wildlife Habitat Connectivity Working Group as well as work by the Western Governors' Association and the Nature Conservancy. They can be used to create resistance, habitat, and core area maps used by Linkage Mapper, Circuitscape, and other connectivity software packages.

Download Gnarly Landscape Utilities here.

Version 0.1.9, released Aug 2, 2016.

You can also see our project on Github.

If you use these tools, please cite them so others can find them!

Citation for Core Mapper:

Shirk, A.J., and B.H. McRae. 2013. Gnarly Landscape Utilities: Core Mapper User Guide. The Nature Conservancy, Fort Collins, CO. Available at:

Citation for Resistance and Habitat Calculator:

McRae, B.H., A.J. Shirk, and J.T. Platt. 2013. Gnarly Landscape Utilities: Resistance and Habitat Calculator User Guide. The Nature Conservancy, Fort Collins, CO. Available at: https://.org/gnarly-landscape-utilities/.


Andrew Shirk, Climate Impacts Group, University of Washington

Brad McRae, The Nature Conservancy

Jim Platt, The Nature Conservancy


These tools were developed for projects supported by the Great Northern Landscape Conservation Cooperative, the North Pacific Landscape Conservation Cooperative, and the Doris Duke Charitable Foundation.