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“The site regularly holds significant numbers of a regionally threatened species, or other species, subspecies, or flyway populations of regional conservation concern.”

Under this criterion, sites are identified for those species that are not globally threatened, but for which there is ample reason to believe that conservation actions are necessary to sustain them. This criterion is also used to identify sites for threatened flyway populations or populations of subspecies that would not otherwise be included in Criterion A1.

Applying B1 Criterion
The thresholds used for criterion B1 are determined by threat status, dispersion pattern, and population size.

• The B1 species have been classified into two threat categories:
  - WatchList ‘Red light’ and federally threatened or endangered (T&E) species
  - WatchList ‘Yellow light’ and ‘Birds of Conservation Concern’ (BCC) species
• B1 population thresholds have been modified to take into consideration the season-dependent dispersion patterns of each species. Thresholds for dispersed species are further modified based on taxonomy (passerine versus non-passerine), following procedures used by BirdLife International in Africa.
• Population scores are used to further refine the population thresholds for identifying IBAs under criterion B1. For each lower population size score (higher abundance) the thresholds are raised.

Population thresholds that must be regularly met at a site for it to qualify as an IBA at the B1 level are as follows. It is expected that threshold numbers be supported simultaneously.

See B1 List (Species of Continental Conservation Concern)

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