IBA Site Criteria

Northern Harrier at Daniel Webster Wildlife Sanctuary © D. Wauchope
Northern Harrier at Daniel Webster Wildlife Sanctuary © D. Wauchope

An Important Bird Area (IBA) is a site that provides essential habitat to one or more species of breeding, wintering, or migrating birds. Important Bird Areas generally support high-priority species, large concentrations of birds, exceptional bird habitat, and/or have substantial research or educational value.

IBA Criteria Categories

  • Category 1: Sites regularly holding significant numbers of an endangered, threatened, vulnerable, or declining species.
  • Category 2: Sites regularly holding significant numbers of species of high conservation priority in Massachusetts.
  • Category 3: Sites where birds concentrate in significant numbers in the breeding season, in winter, or during migration.
  • Category 4: Sites containing assemblages of species characteristic of a representative, rare, threatened, or unique habitat within the state or region.
  • Category 5: Sites important for long-term research and/or monitoring projects that contribute substantially to ornithology, bird conservation, and/or education.

Additional Information

Sites may be protected or unprotected, public or private. The sites may vary in size but are usually discrete and distinguishable in character, habitat, or ornithological importance from surrounding areas. Site boundaries may be either natural (e.g., rivers, watersheds) or human-made (e.g., roads, property boundaries). In general, an IBA should exist as an actual or potential protected area or should have the potential to be specifically managed for bird conservation.

An IBA, whenever possible, should be large enough to supply all or most of the needs of birds during the season for which the IBA is important. Not all IBAs can or will meet this last definition—for example, "flyover" sites for raptors.

A site that meets any one of the criteria in the five categories listed above may qualify as an Important Bird Area—some sites may meet several criteria. These criteria should not be considered absolute; other factors, such as relative importance compared to other sites, may be considered when making the final site selections.

Category 5 (Important Bird Research Areas) is included to cover sites that are important to bird conservation because of the research done there.

The criteria for what constitutes an IBA in Massachusetts were developed with the help of a committee of bird experts from throughout the state.

Learn more about the Site Nomination Process >