Vertebrate Models

Overview | Amphibians | Birds | Mammals | Reptiles | Total Species

The purpose of the GAP vertebrate species maps is to provide more precise information about the current predicted distribution of individual native species within their general ranges. With this information, better estimates can be made about the actual amounts of habitat area and the nature of its configuration.

Gap analysis uses the predicted distributions of animal species to evaluate their conservation status relative to existing land management. However, the maps of species distributions may be used to answer a variety of management, planning and research questions relating to individual species or groups of species. In addition to the maps, great utility may be found in the consolidated specimen collection records and literature that are assembled into databases used to produce the maps.

Previous to this effort there were no maps available, digital or otherwise, showing the likely present-day distribution of species by habitat type across their ranges. Because of this, ordinary species (i.e., those not threatened with extinction or not managed as game animals) are generally not given sufficient consideration in land-use decisions in the context of large geographic regions or in relation to their actual habitats. Their decline because of incremental habitat loss can, and does, result in one threatened or endangered species “surprise” after another. Frequently, the records that do exist for an ordinary species are truncated by state boundaries. Simply creating a consistent spatial framework for storing, retrieving, manipulating, analyzing and updating the totality of our knowledge about the status of each animal species is one of the most necessary and basic elements for preventing further erosion of biological resources.


Modeling of vertebrate distributions for GA-GAP generally followed a 7-step process.

  1. Compiled a list of species to be modeled in Georgia.
  2. Collected occurrence and habitat association data for each species.
  3. Used the occurrence data to approximate the range boundaries of each species in Georgia.
  4. Assembled the habitat association information into a Microsoft Access database and produced printed copies of initial range maps.
  5. Biologists familiar with the distribution of Georgia’s wildlife reviewed the models and range boundaries.
  6. Combined the range approximations with habitat associations to produce a GIS model of the predicted distribution of each species.
  7. Conducted an accuracy assessment of the predicted distributions.

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