Most Endemic Bird Areas are in the tropics and important for other biodiversity too
A total of 218 Endemic Bird Areas has been identified across the world, the majority in the tropics and subtropics. There is good congruence between global patterns of bird endemism, as shown by Endemic Bird Areas, and those shown by other biodiversity, including other terrestrial vertebrates, invertebrates and plants for which data are available.
An Endemic Bird Area (EBA) is defined as an area that encompasses the overlapping breeding ranges of two or more restricted-range landbirds, such that the complete ranges of at least two species fall entirely within the boundary of the EBA.
Following this simple definition, a total of 218 EBAs has been identified across the world (see map), covering the ranges of 93% of restricted-range birds (2,451 species). The majority of EBAs (77%) are in the tropics and subtropics.
There are approximately equal numbers of island EBAs (105) and mainland EBAs (113). Of the island EBAs, 70% are on oceanic islands, 30% on continental-shelf islands, while for the mainland ones, 42% are largely in montane areas, 35% in lowland areas and 24% span both.
The predominant natural habitat in most EBAs (c.80%) is forest, especially tropical lowland and montane moist forest. The number of restricted-range landbirds occurring in EBAs varies from two to over 50 (the richest EBAs are the Solomon Islands, the Chocó in Colombia and Ecuador and the Atlantic Forest lowlands in Brazil) (Stattersfield et al. 1998).
There is good congruence between global patterns of bird endemism, as shown by EBAs, and those shown by other biodiversity, including other terrestrial vertebrates, invertebrates and plants for which data are available.
Overall, more than 50% of EBAs are significant centres of endemism for at least one of these major groups, although their relative importance for different groups is not always the same. For example, ‘Centres of Plant Diversity’ (CPDs—234 areas with high diversity and/or endemism for plants) (WWF/IUCN 1994, 1994–1995, 1997) and EBAs show good congruence: overall, 70% of CPDs overlap with EBAs, and 60% of EBAs overlap with CPDs.
EBAs have also been shown to be excellent indicators of vertebrate and plant diversity patterns in sub-Saharan Africa, due to the common ecological and evolutionary principles on which species’ distributions are based.
Endemic Bird Areas EBA Summary
Most bird species are quite widespread and have large ranges. However, over 2,500 are restricted to an area smaller than 50,000 km2, and they are said to be endemic to it. BirdLife has identified regions of the world where the distributions of two or more of these restricted-range species overlap to form Endemic Bird Areas.
EBAs contain nearly all of the world’s restricted-range bird species – only 7% of restricted-range species do not overlap with other such species and therefore do not occur in EBAs.
The EBAs also support many of the world’s more widespread bird species. Half of all restricted-range species are globally threatened or near-threatened and the other half remain forever vulnerable to the loss or degradation of habitat owing to the small size of their ranges.
The majority of EBAs are also important for the conservation of restricted-range species from other animal and plant groups. For example, there is an overlap of 70% between the location of EBAs and areas which are similarly important for endemic plants globally.
The unique landscapes where these species occur, amounting to just 4.5% of the earth’s land surface, are high priorities for broad-scale ecosystem conservation.
The natural habitat in most EBAs (83%) is forest, especially tropical lowland forest and moist montane forest. Altogether, remaining suitable habitat within the EBAs now covers only 7,300,000 km2, a small proportion of the Earth’s land area.
Geographically, EBAs are often islands or mountain ranges, and they vary considerably in size, from a few square kilometres to more than 100,000 km2, and in the numbers of restricted-range species that they support (from 2 to 80). EBAs are found around the world, but most (77%) of them are located in the tropics and subtropics.
An Endemic Bird Area (EBA) is defined as an area which encompasses the overlapping breeding ranges of restricted-range species, such that the complete ranges 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.
Restricted-range species are defined as all landbirds that have had, throughout historical times (since ornithological recording began after 1800), a total global breeding range estimated at below 50,000km2.
Species with historical ranges estimated to be above this threshold, but which have been reduced to below 50,000km2 by habitat loss or other pressures, are not covered as EBAs should represent natural areas of endemism for birds. In the identification of the current list of EBAs, restricted-range landbirds that have become extinct since 1800 were included to help identify areas of high concentrations of endemic species.
For full details of the methodologies used, please see:
Stattersfield, A.J., Crosby, M.J., Long, A.J. and Wege, D.C. (1998) Endemic Bird Areas of the World. Priorities for biodiversity conservation. BirdLife Conservation Series 7. Cambridge: BirdLife International.
Vietnam Endemic Bird Areas (EBAs)