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 surveys—not 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 regionally significant.

a. 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 Bonaparte’s 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.

b. 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.

c. 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.

d. Raptors

  • The site is a bottleneck or migration corridor for more than 5,000 migratory raptors during a migration season.

e. 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 phalaropes.

f. 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.

g. 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.