Gap Analysis Project (GAP) Terrestrial Vertebrate Species Richness Maps for the Conterminous U.S.

Scientific Investigations Report 2019-5034
Prepared in cooperation with North Carolina State University, New Mexico State University, and Boise State University
By: , and 



The mission of the Gap Analysis Project (GAP) is to support national and regional assessments of the conservation status of vertebrate species and plant communities. This report explains conterminous United States species richness maps created by the U.S. Geological Survey for four major classes in the phylum Chordata: mammals, birds, reptiles, and amphibians. In this work, we focus on terrestrial vertebrate species and the spatial patterns of richness derived from species’ habitat distribution models. We created species’ habitat distribution models for 1,590 species (282 amphibians, 621 birds, 365 mammals, 322 reptiles) and an additional 129 subspecies (2 amphibians, 28 birds, 94 mammals, 5 reptiles) that occur in the conterminous United States. The 1,590 species level models were spatially combined to create the taxa richness maps at a spatial resolution of 30 meters. Based on those maps we identified the maximum species richness for each of the taxa (43 amphibians, 163 birds, 72 mammals, and 54 reptiles) and show variation in richness across the conterminous United States. Because these habitat models remove unsuitable areas within the range of the species, the patterns of richness presented here are different from the coarse-resolution species’ habitat distribution models commonly presented in the literature. These maps provide a new, more spatially refined richness map. In addition, since these models are logically linked to mapped data layers that constitute habitat suitability, this suite of data can provide an intuitive data system for further exploration of biodiversity and implications for change at ecosystem and landscape scales.

Suggested Citation

Gergely, K.J., Boykin, K.G., McKerrow, A.J., Rubino, M.J., Tarr, N.M., and Williams, S.G., 2019, Gap Analysis Project (GAP) terrestrial vertebrate species richness maps for the conterminous U.S.: U.S. Geological Survey Scientific Investigations Report 2019–5034, 99 p.,

ISSN: 2328-0328 (online)

Table of Contents

  • Abstract
  • Introduction
  • Methods
  • GAP Wildlife Habitat Relations Models (WHRMs) and Their Associated Habitat Maps Can be Useful in the Following Applications
      The Species Habitat Distribution Maps
      Other Literature Related to GAP Species Habitat Distribution Models
  • Data Access
  • Results
  • Programmatic Considerations
  • References Cited
  • Appendix 1. Ancillary Datasets and Model Parameter Used in Species’ Habitat Modeling
  • Appendix 2. Selected References for Information Used to Delineate Species’ Ranges
  • Appendix 3. Table of Notes on Species Taxonomy
  • Appendix 4. Table of Ancillary Datasets
Publication type Report
Publication Subtype USGS Numbered Series
Title Gap Analysis Project (GAP) Terrestrial Vertebrate Species Richness Maps for the Conterminous U.S.
Series title Scientific Investigations Report
Series number 2019-5034
DOI 10.3133/sir20195034
Year Published 2019
Language English
Publisher U.S. Geological Survey
Publisher location Reston VA
Contributing office(s) Core Science Analytics and Synthesis, GAP Analysis Project
Description v, 99 p.
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details