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Species Vision

Our goal is to build species range and predicted habitat maps with the best available data for assessing conservation status, conservation planning, and research (e.g., climate change impacts). These data are intended to describe patterns of species geographic location and basic ecological characteristics (e.g., habitat associations). Spatial patterns of species occurrence across landscapes can provide insights into biodiversity conservation (e.g., species richness).

Strategy

In 2008, GAP embarked on an effort to begin creating species habitat maps across entire species ranges within the continental US (CONUS). We started by creating a species list for the US based on  previous  GAP efforts for the Southwest (SWReGAP), Southeast (SEGAP), and Northwest (NWGAP). We then compiled species lists from all the remaining states (e.g., California, Midwestern and Northeastern states). Once a comprehensive list was created, each species was verified using the most current information regarding that species (Crother 2008, Wilson and Reeder 2005, American Ornithological Union’s 2008 checklist).

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 occurence (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 continental US (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 insight become available and will provide the basis of a national biodiversity assessment.

Current Status

As a result of our current deductive modeling, we also have created core data needed for conducting national species modeling. This includes a national wildlife habitat relationship database on which all our current deductive modeling efforts are based. This database contains wildlife habitat relationships to land cover and other spatial habitat parameters (e.g., elevation, slope) based on literature and expert opinion.

We intend to continue with our deductive modeling while simultaneously gearing up our inductive modeling effort, which will require a species point occurrence database and national spatial environmental layers, such as temperature and precipitation. We view modeling as an iterative process in which we will update our ranges and models as new data and information become available. Revisions to existing models will be issued on a quarterly basis when warranted.

Our next modeling effort will focus on revising the full suite of species data with CONUS 2016 land cover data along with developing assessments of the existing CONUS 2001 data.