U.S. Geological Survey Gap Analysis Program Species Distribution Models

GAP distribution models represent the areas where species are predicted to occur based on habitat associations. GAP distribution models are the spatial arrangement of environments suitable for occupation by a species. In other words, a species distribution is created using a deductive model to predict areas suitable for occupation within a species range.

To represent these suitable environments, GAP compiled existing GAP data, where available, and compiled additional data where needed. Existing data sources were the Southwest Regional Gap Analysis Project (SWReGAP) and the Southeast Gap Analysis Project (SEGAP) as well as a data compiled by Sanborn Solutions and Mason, Bruce and Girard. Habitat associations were based on land cover data of ecological systems and--when applicable for the given taxon--on ancillary variables such as elevation, hydrologic characteristics, human avoidance characteristics, forest edge, ecotone widths, etc.

Distribution models were generated using a python script that selects model variables based on literature cited information stored in a wildlife habitat relationship database (WHRdb); literature used includes primary and gray publications. Distribution models are 30 meter raster data and delimited by GAP species ranges. Distribution model data were attributed with information regarding seasonal use based on GAP regional projects (NWGAP, SWReGAP, SEGAP, AKGAP, HIGAP, PRGAP, and USVIGAP), NatureServe data, and IUCN data.

A full report documenting the parameters used in each species model can be found via: http://gis1.usgs.gov/csas/gap/viewer/species/Map.aspx

Web map services for species distribution models can be accessed from:
http://gis1.usgs.gov/arcgis/rest/services/NAT_Species_Birds
http://gis1.usgs.gov/arcgis/rest/services/NAT_Species_Mammals
http://gis1.usgs.gov/arcgis/rest/services/NAT_Species_Amphibians
http://gis1.usgs.gov/arcgis/rest/services/NAT_Species_Reptiles

A table listing all of GAP's available web map services can be found here: http://gapanalysis.usgs.gov/species/data/web-map-services/

GAP used the best information available to create these species distribution models; however GAP seeks to improve and update these data as new information becomes available.

Recommended citation: U.S. Geological Survey Gap Analysis Program (USGS-GAP). [Year]. National Species Distribution Models. Available: http://gapanalysis.usgs.gov. Accessed [date].

Online references:
U.S. Geological Survey Gap Analysis Program: http://gapanalysis.usgs.gov
Northwest Gap Analysis Project: http://gap.uidaho.edu
Southwest Regional Gap Analysis Project: http://swregap.nmsu.edu/HabitatModels/default.htm
Southeast Gap Analysis Project: http://www.basic.ncsu.edu/segap
Alaska Gap Analysis Project: http://aknhp.uaa.alaska.edu/zoology/akgap
Hawaii Gap Analysis Project: ftp://ftp.gap.uidaho.edu/products/Hawaii.zip