At the European (=regional) level, three criteria have been applied to identify IBAs for congregatory species of birds, species of conservation concern in Europe and species that are largely restricted to Europe. A further six IBA criteria were developed exclusively for use within the European Union (=sub-regional criteria) to identify sites that comply with the requirements of Special Protection Areas (SPAs) designated under the Wild Birds Directive.

B: European IBA criteria

B1. Congregations

i. The site is known or thought to hold ≥ 1% of a flyway or other distinct population of a waterbird species.

ii. The site is known or thought to hold ≥ 1% of a distinct population of a seabird species.

iii. The site is known or thought to hold ≥ 1% of a flyway or other distinct population of other congregatory species.

iv. The site is a ‘bottleneck’ site where over 5,000 storks, or over 3,000 raptors or cranes regularly pass on spring or autumn migration.

B2. Species with an unfavourable conservation status in Europe

The site is one of the 'n' most important in the country for a species with an unfavourable conservation status in Europe (SPEC1/2/3) and for which the site-protection approach is thought to be appropriate.

B3. Species with a favourable conservation status in Europe

The site is one of the 'n' most important in the country for a species with a favourable conservation status in Europe but concentrated in Europe (Non-SPEC^E [previously, SPEC4]) and for which the site-protection approach is thought to be appropriate.

C: European Union

C1. Species of global conservation concern

The site regularly holds significant numbers of a globally threatened species, or other species of global conservation concern.

C2. Concentrations of a species threatened at the European Union level

The site is known to regularly hold at least 1% of a flyway population or of the EU population of a species threatened at the EU level (listed on Annex I and referred to in Article 4.1 of the EC Birds Directive).

C3. Congregations of migratory species not threatened at the EU level

The site is known to regularly hold at least 1% of a flyway population of a migratory species not considered threatened at the EU level (as referred to in Article 4.2 of the EC Birds Directive) (not listed on Annex I).

C4. Congregatory – large congregations

The site is known to regularly hold at least 20,000 migratory waterbirds and/or 10,000 pairs of migratory seabirds of one or more species.

C5. Congregatory – bottleneck sites

The site is a ‘bottleneck’ site where at least 5,000 storks (Ciconiidae) and/or at least 3,000 raptors (Accipitriformes and Falconiformes) and/or 3,000 cranes (Gruidae) regularly pass on spring or autumn migration.

C6. Species threatened at the European Union level

The site is one of the five most important in the European region (NUTS region) in question for a species or subspecies considered threatened in the European Union (i.e. listed in Annex I of the EC Birds Directive).

Notes: The “n” in criteria B2 and B3 indicates the maximum number of sites that can be identified in any given country and is proportional to the minimum size of the national population relative to the minimum estimate of the total European population. The country should hold a least 1% of the European population and each site should hold at least 1% of the national population.