Massachusetts Important Bird Areas
IBA Criteria Category 3
Sites where birds concentrate in significant numbers in the breeding season,
in winter, or during migration.
Sites that regularly support significant numbers
of one or more species during the breeding, nonbreeding, or migration
seasons. Except where indicated, numerical estimates should be based
on a short period of time, e.g., one-time counts such as daily surveysnot
on cumulative totals. Introduced and feral species should not be counted.
The numerical criteria categories below are guidelines
only. Other factors, such as the quality and location of habitat,
along with the distribution and importance of species, may also be
considered. Lower numbers will be considered for inland sites where,
with species such as waterfowl, concentrations are smaller but are
- Seabirds: The
site regularly supports 300 or more pelagic seabirds and/or terns
or 3,000 or more gulls at one time. A pelagic site is the actual location
being used by seabirds (e.g., Stellwagen Bank) and not the location
from which an observer counts seabirds (e.g., Provincetown). Smaller
concentrations of less common gulls such as Laughing or Bonapartes
gullswill be considered. Human-made food sources for gulls such as
landfills and sewage outflows will not be considered. The designation
"seabirds" includes shearwaters, storm-petrels, fulmars,
gannets, jaegers, and alcids.
- Wading Birds: The site regularly supports 25 or more breeding pairs
of wading birds or 100 or more foraging individuals (at one time)
during migration. The designation "wading birds" includes
bitterns, herons, egrets, and ibises.
- Waterfowl: The site regularly supports 500 or more waterfowl at
any one time. The designation "waterfowl" includes birds
such as loons, grebes, cormorants, geese, ducks, coots, and moorhens.
- Raptors: The site is a bottleneck or migration
corridor for more than 5,000 migratory raptors during a migration
- Shorebirds: The site regularly supports
1,000 or more shorebirds at one time at a coastal site, during some
part of the year, or a significant concentration of shorebirds at
one time at a nontidal site. The designation "shorebirds"
includes birds such as plovers, sandpipers, snipe, woodcocks, and
- Land Birds: The site is an important migratory
stopover or seasonal concentration site for migratory land birds (e.g.,
warblers). Sites may also qualify on the basis of supporting exceptionally
high densities of breeding species as shown from point counts or other
surveys or if they represent "migrant traps" relative to
surrounding areas. Strong consideration will be given to areas with
consistently high overall species diversity.
- Single-species Concentrations: The site
regularly supports significant concentrations of a flocking species,
but may not meet the thresholds above. The site should support a higher
proportion of a species' statewide population (more than 1%, if known)
than other similar sites.
View Criteria Category (1), (2), (3),