IBAs Criteria

Globally Threatened species

The site regularly holds significant numbers of a Globally Threatened species, or other species of global conservation concern. This category refers to species classified as globally threatened with extinction, Vulnerable, Endangered or Data Deficient according to the new IUCN criteria (link to for threatened status. The site qualifies if it is known, estimated or thought to hold a population of a species as categorized to this new IUCN criteria. Population-size thresholds for globally threatened species are set regionally, as appropriate, to help in site selection.

Restricted Range Species

The site is known or thought to hold a significant component of the restricted-range species whose breeding distributions define an Endemic Bird Area (EBA) or Secondary Area (SA).

A Restricted Ranges bird species is a landbird which has had, throughout historical times (i.e. post 1800 AD, in the period since ornithological recording began), a total global breeding range estimated at below 50,000 sq. km. Species with historical ranges estimated to be above this threshold, but which have been reduced to below 50,000 sq. km by habitat loss or other pressures, were not covered because the EBA project seeks to locate natural areas of endemism for birds, which are also likely to be important for other unique animals and plants (although it is recognized that many species' ranges may have been severely altered by human impact prior to 1800 AD). Restricted range landbirds which have become extinct since 1800 AD were included in the analysis, because they have helped to identify areas which have concentrations of such taxa (Stattersfield et al. 1998). Seabirds were excluded from the analysis because their distributions are determined by different factors to those which affect landbirds and other terrestrial taxa, and they are therefore considered to be best treated as a separate group for conservation purpose (Stattersfield et al. 1998).

An Endemic Bird Area (EBA) is defined as an area which encompasses the over-lapping breeding ranges of restricted-range bird species, such that the complete range of two or more restricted-range species are entirely included within the boundary of the EBA. This does not necessarily mean that the complete ranges of all of an EBA's restricted-range species are entirely included within the boundary of that single EBA, as some species may be shared between EBAs (Stattersfield et al. 1998).

Endemic Bird Areas relevant to India:

  1. Western Ghats (EBA 123)
  2. Andaman Islands (EBA 125)
  3. Nicobar Islands (EBA 126)
  4. Western Himalayas (EBA 128)
  5. Eastern Himalayas (EBA 130)
  6. Assam Plains (EBA 131)
  7. Southern Tibet (EBA 133) (Though the area primarily lies in Tibet, portions of it also extend into India)

Secondary areas

A Secondary Area is an area which supports one or more restricted-range bird species, but does not qualify as an EBA because fewer that two species are entirely confined to it. Typically Secondary Areas include single restricted-range species which do not overlap in distribution with any other such species, and places where there are widely disjunct records of one or more restricted-range species (Stattersfield et al . 1998). For example, Tadoba IBA is considered as a Secondary Area as it has only Forest Owlet as restricted-range species.

Secondary Areas in India:

  1. Eastern Andhra Pradesh (SA: 071)
  2. Southern Deccan plateau (SA: 072)
  3. Indus plains (SA: 074)
  4. Central Indian Forests (SA: 075)
  5. North Myanmar lowlands (mainly in Myanmar but also includes lowlands of India) (SA: 079)

Biome-Restricted Assemblages

The site is known or thought to hold a significant component of the group of species whose distributions are largely or wholly confined to one biome.

A biome may be defined as a major regional ecological community characterised by distinctive life forms and principal plant species (Crosby 1997). No system of global biome classification has been found which can be adequately used as a basis for generating bird species lists. Therefore, it is necessary that we should have a regional approach, which may result in inter-regional differences but may be comparable at the overall scale at which biome divisions are recognised.

This category applies to groups of species with largely shared distributions of greater that 50,000 sq. km, which occur mostly or wholly within all or part of a particular biome and are, therefore, of global importance.

A4i Congregations

This category applies to those species that congregate at sensitive sites when breeding or wintering, or while on passage. The term ‘water-bird' is used here in the same sense as the Ramsar Convention uses ‘waterfowl' and covers the list of families more precisely defined by Wetlands International. Congregatory non-waterbird species (A4ii) include both terrestrial species and families of seabird such as Procellaridae, Hydrobatidae, Pelecanididae, Phaethontidae, Sulidae, and Fregatidae .

(A4i) Site known or thought to hold, on a regular basis, 1% of a biogeographic population of a congregatory waterbird species. For the thresholds of this criterion, relevant flyway populations are combined to produce biogeographic population estimates.


Site known or thought to hold, on a regular basis, 1% of the global population of a congregatory seabird or terrestrial species. This category covers non-water bird or terrestrial birds or sea birds.


Site known or thought to hold, on a regular basis, 20,000 waterbirds or 10,000 pairs of seabirds of one or more species. Use of this criterion is discouraged where data quality permits A4i and A4ii to be used.


Site known or thought to be a ‘bottleneck site' where at least 20,000 storks (Ciconiidae), raptors (Accipitriformes and Falconiformes) or cranes (Gruidae) pass regularly during spring or autumn migration.