Species Vision

Science Center Objects

Our goal is to build species range and predicted habitat maps to support state, regional, and national biodiversity assessments for the conservation status of native vertebrate species and to facilitate the application of this information to land management activities. These data are intended to describe patterns of species geographic location and basic habitat associations.

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GAP data are used to assess the status of biodiversity in the US by mapping where species habitats exist and to evaluate the likelihood of persistence of those habitats. The most common analysis is to perform a “gap analysis”, or to evaluate where the system of protected areas in the US provides inadequate habitat coverage for a species or group of species. Vertebrate diversity has been the ongoing focus of analysis for GAP, with the assumption that, lacking sufficient data, vertebrates and their associated habitats are a reasonable, yet imperfect, measure of biodiversity because these species are responding to landscape level variation in vegetation and environmental conditions at a resolution that is meaningful for management and can serve as a coarse-filter for conservation planning (Noss and Cooperrider 1987, Csuti and Kiester 1996).

Photo of elk with plains and mountains in background

Elk, Great Sand Dunes National Park, Colorado

(Public domain.)

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 modified version of national sub-watersheds (12-digit hydrologic units or HUCs). Each sub-watershed is attributed with values of occurrence (extant, possibly present, potentially present, extirpated), season (year-round, summer, winter, migratory, vagrant), reproductive use (breeding, non-breeding, both) and origin (native, introduced, reintroduced, vagrant). A variety of data sources were utilized including regional GAP data sets, NatureServe, and primary literature. See the metadata for more information. We are using each species' range to provide the spatial extent within which to build our species 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 model to predict areas suitable for occupation within a species’ range. Our predicted habitat maps, which are the result of our distribution models, are created at a 30m2 resolution. While we have used point observation data to develop inductive models in regional efforts when appropriate, we primarily are using deductive modeling approaches based on habitat associations and expert input for the CONUS data set. For more information see the metadata.

The conterminous U.S. (CONUS) data release is our first data set of species models applied across continental ranges rather than stopping at state or regional boundaries. These data will provide a base from which we can iteratively improve the model when new data and insights become available and will provide the basis of a national biodiversity assessment.

Csuti, B., and Kiester A.R., 1996, Hierarchical gap analysis for identifying priority areas for biodiversity. In Gap Analysis: A Landscape Approach to Biodiversity Planning. Editors J. M. Scott, T. H. Tear, and F. W. Davis. American Society for Photogrammetry and Remote Sensing. Bethesda, MD.

Morrison, M. L., and Hall, L.S., 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.

Noss, R. F. and Cooperrider, A.Y., 1994, Saving Nature’s Legacy: Protecting and Restoring Biodiversity. Island Press. Washington D.C. 341 pp.


Current Status

We created species habitat distribution models for 1590 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 U.S. (CONUS). Those models are based on 2001 habitat conditions. In addition, we have species models for Alaska, Hawaii, Puerto Rico and the U.S. Virgin Islands.

Currently we are conducting the species and taxa level conservation assessments using the species data. Our next modeling effort will focus on revising the full suite of species data with CONUS 2016 land cover.