Species range maps and distribution models
Knowledge of a species’ geographic and ecological location is fundamental to conservation planning, conservation forecasting (e.g., climate change), and for understanding spatial patterns of species occurrence (e.g., species richness, historical vs. current). To contribute towards the knowledge regarding species geographic and ecological locations, USGS-GAP is creating species distribution models across entire species ranges for more than 2,000 species that occur within the continental US as well as Alaska, Hawaii, Puerto Rico, and the U.S. Virgin Islands. Our goal is to build species range maps and distribution models with the best available data for assessing conservation status, conservation planning, and research (e.g., climate change impacts). These ranges and models represent a base on which we will build upon as new data become available. Furthermore, they will provide the basis of a national biodiversity assessment.
To date, we have a portion of our total species available through the GAP Species Viewer. As more species ranges and distribution models are completed, we will continually update our data on the GAP Species Viewer. Please check back for updates.
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Get current status of species range and distribution models (163 kb, csv file)
GAP Species Data Features:
Species list
We created our species lists for the U.S. by initially compiling the species lists for our regional projects in the Southwest (SWReGAP), Southeast (SEGAP), and Northwest (NWGAP). We then filled in areas not represented by these regional projects with species lists from all the remaining states (e.g., California, Midwestern and Northeastern states). Once a comprehensive list was compiled, each species’ taxonomic classification was verified using the most current information available (Banks et al. 2008, Crother 2008, Wilson and Reeder 2005).
Range maps
We defined a species range as a coarse representation of the total areal extent of a species or the geographic limits within which a species can be found (Morrison and Hall 2002). To represent these geographic limits, we used a national database of standardized 12-digit hydrological units (HUCs; U.S. Geological Survey and U.S. Department of Agriculture, Natural Resources Conservation Service 2009). Ranges maps were compiled and attributed with information from SWReGAP, SEGAP, NatureServe, and IUCN. Each range map contains information regarding occurrence/presence, origin, reproductive use, and seasonal use.
Distribution models
We defined a species distribution as 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. Currently, we are focusing our efforts on building, expanding, or updating our deductive species models, but we will also expand our inductive modeling efforts over time. For species entirely within one of our regional projects, we are using existing distribution models created by those respective efforts as our national distribution model.
Additional data
Several key national ancillary data layers (e.g., elevation, stream velocity, distance to forest edge, etc.) have been created for our national modeling effort and are available for download.
How to cite these data
Range maps
U.S. Geological Survey Gap Analysis Program. 2011. National GAP vertebrate species range data. gapanalysis.usgs.gov.
Distribution models
U.S. Geological Survey Gap Analysis Program. 2011. National GAP vertebrate species distribution model. gapanalysis.usgs.gov
For citation information for additional GAP species modeling data, see our metadata.
Literature Cited
Banks, R. C., R. T. Chesser, C. Cicero, J. L. Dunn, A. W. Kratter, I. J. Lovette, P. C. Rasmussen, J. V. Remsen, Jr., J. D. Rising, D. F. Stotz, and K. Winker. 2008. Forty-ninth supplement to the American Ornithologists’ Union Check-list of North American Birds. The Auk 125:758-768.
Crother, B. I. 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. 6th edition. Herpetological Circular No. 37, Society for the Study of Amphibians and Reptiles.
Morrison, M. L., and L. S. Hall. 2002. Standard terminology: Toward a common language to advance ecological understanding and application. Pages 43-52 in Predicting Species Occurrences: Issues of accuracy and scale. Editors: J. M. Scott, P. J. Heglund, and M. L. Morrison, et al., Island Press.
U.S. Geological Survey and U.S. Department of Agriculture, Natural Resources Conservation Service, 2009, Federal guidelines, requirements, and procedures for the national Watershed Boundary Dataset: U.S. Geological Survey Techniques and Methods 11–A3, 55 p.
Wilson, D. E., and D. M. Reeder. 2005. Mammal Species of the World. A Taxonomic and Geographic Reference, 3rd edition. Johns Hopkins University Press.