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Location Seychelles
Central coordinates 46o 22.00' East  9o 26.00' South
IBA criteria A1, A2, A4i, A4ii, A4iii
Area 33,180 ha
Altitude 0 - 8m
Year of IBA assessment 2001

Nature Seychelles

Site description Aldabra is the world’s largest raised coralline atoll. It is situated 640 km east of the African continent, 420 km north-west of Madagascar, and 1,100 km south-west of Mahé. It comprises four main islands circling a central lagoon, Grande Terre, Malabar, Picard and Polymnie. There are many smaller islands and islets, some of which are rat-free. The land area comprises 15,380 ha, the lagoon 22,400 ha, and the IBA also includes a coastal marine area of 10,700 ha. The terrain is characterized by irregular limestone formations called ‘champignon’. The vegetation is dense and shrubby, adapted to relatively low rainfall and strong winds, and dominated in large areas by Pemphis acidula. Around 15% of the land area is more open, and covered in low grasses known as ‘tortoise turf’. The inner rim of the lagoon is lined with mangroves. The flora is exceptionally rich in endemics, with 19 species restricted to Aldabra and 22 others found also only on other islands of the Aldabra group. There is also a pristine marine ecosystem, with an intact fringing reef and an abundant and diverse fish and invertebrate fauna. A small permanent human population is based on Picard, engaged in wardening the reserve and scientific research. There are several huts on the other main islands for the overnight accommodation of scientists and fieldworkers. In the past, the islands were exploited for mangrove wood, turtles and giant land tortoises.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Egretta garzetta breeding  1,000-3,000 breeding pairs  A4i  Not Recognised 
Madagascar Pond-heron Ardeola idae breeding  20-50 breeding pairs  A1, A4i  Endangered 
Red-tailed Tropicbird Phaethon rubricauda breeding  1,900 breeding pairs  A4ii  Least Concern 
White-tailed Tropicbird Phaethon lepturus breeding  2,500 breeding pairs  A4ii  Least Concern 
Great Frigatebird Fregata minor breeding  4,000 breeding pairs  A4ii  Least Concern 
Lesser Frigatebird Fregata ariel breeding  6,000 breeding pairs  A4ii  Least Concern 
Red-footed Booby Sula sula breeding  6,000-7,000 breeding pairs  A4ii  Least Concern 
Crab-plover Dromas ardeola winter  2,800 individuals  A4i  Least Concern 
Ruddy Turnstone Arenaria interpres winter  500-1,000 individuals  A4i  Least Concern 
Black-naped Tern Sterna sumatrana breeding  70-150 breeding pairs  A4i  Least Concern 
Comoro Blue-pigeon Alectroenas sganzini resident  1999  present  A2  Least Concern 
Aldabra Drongo Dicrurus aldabranus resident  1999  present  A1, A2  Near Threatened 
Aldabra Warbler Nesillas aldabrana resident  1983  present  A1, A2  Extinct 
Red-headed Fody Foudia eminentissima resident  1999  present  A2  Least Concern 
A4iii Species group - seabirds breeding  50,000-99,999 individuals  unknown  A4iii   

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Aldabra Special Reserve 35,000 protected area contains site 33,180  
Aldabra Atoll World Heritage Site 35,000 protected area contains site 33,180  

Land use

Land-use Extent (% of site)
nature conservation and research -

Other biodiversity Aldabra has the world’s largest population of the giant tortoise Dipsochelys dussumieri, estimated to number c.100,000 individuals in 1997. It is also of global importance for the sea-turtle Chelonia mydas (EN), which comes ashore to nest throughout the year; surveys between 1981–1985 indicated 10,000–18,000 nesting emergences annually; smaller numbers of Eretmochelys imbricata (CR) also breed. There are four species of lizard, including one endemic race Phelsuma abbotti abbotti. There are also four species of bat, including one endemic race of fruit bat, Pteropus seychellensis aldabrensis. A healthy population of the coconut crab Birgus latro (DD) exists throughout the atoll.

Further web sources of information 

Alliance for Zero Extinction (AZE) species/site profile. This site has been identified as an AZE due to it containing a Critically Endangered or Endangered species with a limited range.

Contribute  Please click here to help BirdLife conserve the world's birds - your data for this IBA and others are vital for helping protect the environment.

Recommended citation  BirdLife International (2014) Important Bird Areas factsheet: Aldabra atoll. Downloaded from on 21/10/2014

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