Regulatory Maps: Priority & Estimated Habitats

Priority and Estimated Habitat maps are used for determining whether or not a proposed project must be reviewed by the NHESP for MESA and WPA compliance.

View the most up to date Priority & Estimated habitats (14th Edition Natural Heritage Atlas, August 1, 2017): interactive map viewer

Priority Habitat

Priority Habitat is based on the known geographical extent of habitat for all state-listed rare species, both plants and animals, and is codified under the Massachusetts Endangered Species Act (MESA). Habitat alteration within Priority Habitats may result in a take of a state-listed species, and is subject to regulatory review by the Natural Heritage & Endangered Species Program. 

Additional Resources

Estimated Habitat

Estimated Habitats are a sub-set of the Priority Habitats, and are based on the geographical extent of habitat of state-listed rare wetlands wildlife and is codified under the Wetlands Protection Act (WPA), which does not protect plants. State-listed wetland wildlife species are protected under the Massachusetts Endangered Species Act as well as the Wetlands Protection Act.

Additional Resources

View the Map

Access to Priority and Estimated Habitat maps is provided through a variety of sources:

It is the responsibility of the land owner or project proponent to determine if their project falls within Priority Habitat or Estimated Habitat and requires review. Failure to file under MESA constitutes a violation of the Act and is subject to a fine (pursuant to 10.06).

Updates to the Map

We will re-evaluate the map every 4 years. The current map was released August 1, 2017 (the 14th Edition Natural Heritage Atlas).

Updates are generally due to the following factors:

  • changes to the MESA species list and observation occurrences
    • species are added or removed from the list
    • new observations are accepted into our database
    • areas mapped from old observations (greater than 25 years) are removed
  • latest research about habitat utilization
  • evaluation of regulatory outcomes
  • improved aerial photographs

Additional Resources


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