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Using a variety of distributional data, we have constructed range maps of New
England's vertebrate species. Sources of data for birds
include statewide Breeding Bird Atlas projects and the Breeding Bird Survey.
Data sources for mammals and for
reptiles and amphibians also include
atlas project data, but also rely heavily on data from Natural Heritage programs.
An example for willow flycatcher illustrates the process of range map development:

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Breeding bird atlas occurences and other sources of data are
brought online and consolidated. This flycatcher distribution map
shows breeding bird atlas blocks where this bird was found.
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Species occurrence records are then used to populate hexagons producing
a hexagon-based map of that species range in New England. These hexagons
(from the EPA EMAP project) are being used as a standard for National Gap
Analysis vertebrate range maps.
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The hexagon-based range maps are sent out to be reviewed by qualified
experts in each New England state.
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Finally, the hexagon maps will be overlayed with habitat maps to produce
maps of predicted distribution. Habitat maps are created by using
species-habitat associations models to extract appropriate cover types from
a land-cover map.
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You may notice that our range map for willow flycatcher suffers for lack of a detailed
land cover map for the final step (because our land-cover map is still in
progress, we used the AVHRR forest cover map for this example).

Recent work on vertebrate distributions also includes production of regional
range maps that have been smoothed by bioregions (U.S. Forest Service
sections and subsections).

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