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MassGIS Data: NHESP Priority Habitats of Rare Species

August 2021

Areas delineated as Priority Habitats are protected and can include wetlands, uplands, and marine habitats.

Table of Contents



The Priority Habitats of Rare Species datalayer contains polygons representing the geographic extent of Habitat of state-listed rare species in Massachusetts based on observations documented within the last 25 years in the database of the Natural Heritage & Endangered Species Program (NHESP). Priority Habitat polygons are the filing trigger for project proponents, municipalities, and all others for determining whether or not a proposed project or activity must be reviewed by the NHESP for compliance with the (MESA) and its implementing regulations. Areas delineated as Priority Habitats can include wetlands, uplands, and marine habitats. The Priority Habitats presented here are part of the 15th Edition of the Massachusetts Natural Heritage Atlas, and are effective beginning August 1, 2021.

If your project or activity falls within Priority Habitat and does not meet a MESA filing exemption (321 CMR 10.14), then you must file directly with the NHESP pursuant to MESA. For more information, please see the Regulatory Review section of the NHESP website.

The Priority Habitats of Rare Species datalayer is stored in ArcSDE as PRIHAB_POLY.


Priority Habitats were digitized by NHESP scientists from documented observations of state-listed rare species and are based on such factors as reported species movements and known habitat requirements. The polygons were heads-up digitized in ArcGIS 10x and referenced to MassGIS 2019 Aerial Imagery.


The layer's polygon attribute table has the following fields:

PRIHAB_ID A unique identifier for each polygon. This number may be used to identify a Priority Habitat polygon when contacting the NHESP.
VERSION Indicates the effective date of the Priority Habitat polygons, as well as the edition of the Natural Heritage Atlas in which they were presented.

Displaying the Data

Priority Habitats should be displayed as follows:

  • At 1:25,000 scale or smaller (e.g. 1:35,000)
  • Against MassGIS’s 2019 Aerial Images as a reference layer.
  • Using the “NHESP Priority Habitats of Rare Species” legend, which MUST accompany this datalayer on ALL maps.
  • NOTE:  Some Priority Habitats are less than 1 acre in size. To effectively display these small areas on a map, the line thickness of the polygon may need to be increased.


Occurrence records are continually being added, updated, deleted or otherwise modified in the NHESP database. These changes are incorporated into revisions to the Priority Habitats of Rare Species datalayer every four years.

Questions about the creation of this datalayer and its use should be directed to NHESP at 508-389-6360 or natural.heritage@state.ma.us.

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