Biological Rarity Index


The Biological Rarity (Biorarity) Index model is based on the Michigan Natural Features Inventory database of known sightings of threatened, endangered, or special concern species and high quality natural communities. Each record is spatially subset to its habitat using land cover data, stream lines, and rail corridors. The record is then assigned three values based one the species' global status, State status, and occurrence quality rank. These values are multiplied by a likelihood of continued occurrence factor based on the age of the database record. Finally, the scores of all the records in a geographic unit are summed to determine the Biorarity Index for that unit. In this map, two layers are presented: an overview layer approximating the size of townships (36 sq. miles), and a more detailed layer of the actual public land survey sections. Both present the Biorarity Indexes for the records represented in each geographical unit.

Data Availability

This data is available for download as an ESRI shapefile packaged in zip file format


For more information, see the white paper Using Geographic Information Systems to Prepare Sensitive Species Information for Land Use Master Planning

This project was funded in part under the Coastal Zone Management Act of 1972, as amended, Office of Ocean and Coastal Resource Management, National Oceanic and Atmospheric Administration, U.S. Department of Commerce and the Michigan Coastal Management Program, Michigan Department of Environmental Quality.

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