density

Creating a Roadkill Observation Density (aka Hotspot) Map

 

On the IFWIS Roadkill Observation webpage (https://fishandgame.idaho.gov/ifwis/observations/salvage/), click Export Roadkill Data near the lower-right corner of the page.  This leads you to a records filter that allows you to query by species, date observed, highway, and milepost.  Once you have applied the filter(s), the data can be downloaded as an Excel .csv file, which can then be saved as an .xlsx file.  In ArcCatalog, create a point shapefile or geodatabase feature class (right-click the .xlsx file and click ‘Create Feature Class’). In ArcMap, use the Spatial Analyst toolbox --- Density toolset --- Kernal Density or Point Density tools to create roadkill density rasters. Depending on what the output raster is being used for (as a visualization tool, for strict data analysis, etc.) one method may be preferred over the other (read more about the differences).  You can customize the output raster cell size and search radius. ArcMap provides a Spatial Statistics toolbox for Cluster and Outlier Analysis and Hot Spot Analysis that identifies statistically significant hot spots, cold spots, and spatial outliers using Anselin’s Local Moran’s I or Getis-Ord Gi* statistics.

 

BONUS:  Idaho Department of Transportation Average Annual Daily Traffic (AADT) data is available on the INSIDE Idaho website.  The Roadkill and AADT data can be “combined” (think raster math) to create a categorical map that simultaneously reflects roadkill and traffic density.