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Location Seychelles
Central coordinates 47o 34.00' East  9o 42.00' South
IBA criteria A4i, A4ii, A4iii
Area 14,960 ha
Altitude 0 - 8m
Year of IBA assessment 2001

Nature Seychelles

Site description Cosmoledo is a raised coralline atoll in the Aldabra group, lying c.120 km east-south-east of Aldabra atoll, 700 km east of Africa and 400 km north-west of Madagascar. It comprises 13 islands and a few tiny islets (460 ha) surrounding a roughly circular lagoon (c.14,500 ha). The lagoon dries out extensively at low tide. Much of the interior of the atoll is characterized by irregular limestone formations known as ‘champignon’. The vegetation is similar to Aldabra (SC020), dominated by salt-resistant Pemphis acidula, but there are some extensive open grassy areas suitable for three species of ground-nesting seabirds not present on Aldabra (Sula dactylatra, S. leucogaster and Sterna fuscata). The islands of Menai and Grand Ile used to have resident human populations engaged in agriculture, fishing and the exploitation of seabirds, seabird eggs and turtles. However, the atoll has now been abandoned. It is visited by boats from both within Seychelles and from Comoros for the illegal poaching of seabirds, eggs and turtles. Two of the three largest islands (Grand Ile and Ile Sud Ouest) do not appear to have rats and, probably, most or even all islets are rat-free.

Key Biodiversity See Box for key species. The site holds Seychelles’ largest colonies of Sula sula and S. dactylatra, both of which have suffered drastic reductions in numbers elsewhere in the Indian Ocean, including extinction on some islands. Cosmoledo is now the only site in Seychelles with a viable population (c.60 pairs) of S. leucogaster, nesting mainly on Ile du Sud Ouest, with a few on Ile du Nord. Exploitation has greatly reduced numbers of breeding Fregata minor to 10–20 pairs, down from hundreds of pairs in the 1970s. Fregata ariel also once bred, but now may be extinct. Nevertheless, 200–400 non-breeding Fregata minor regularly occur, as do similar numbers of Fregata ariel. The site is the only breeding area in the Aldabra group for Sterna fuscata. It is the largest colony in Seychelles and, perhaps, in the western Indian Ocean. Some 15–30 pairs of Egretta dimorpha also breed. Resident landbirds include three endemic Seychelles races, Zosterops maderaspatana menaiensis (restricted to Cosmoledo and Astove), Nectarinia sovimanga buchenorum (restricted to Cosmoledo and Astove) and a form of Streptopelia picturata. This has been assumed to be coppingeri, but its status is currently under investigation and may prove to be a race restricted to Cosmoledo. Cisticola cherina, believed to be a relatively recent natural colonizer, is common on most islands; it occurs in Seychelles only on Cosmoledo and Astove.

Non-bird biodiversity: Green turtle Chelonia mydas (EN) nest all around the outside of the atoll. They have been heavily exploited and numbers are reduced.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Red-tailed Tropicbird Phaethon rubricauda breeding  50-200 breeding pairs  A4ii  Least Concern 
Sula dactylatra breeding  5,000-6,000 breeding pairs  A4ii  Not Recognised 
Red-footed Booby Sula sula breeding  15,000 breeding pairs  A4ii  Least Concern 
Crab-plover Dromas ardeola winter  2,000 individuals  A4i  Least Concern 
Ruddy Turnstone Arenaria interpres winter  400 individuals  A4i  Least Concern 
Greater Crested Tern Thalasseus bergii breeding  100-500 breeding pairs  A4i  Least Concern 
Black-naped Tern Sterna sumatrana breeding  50-100 breeding pairs  A4i  Least Concern 
Sooty Tern Onychoprion fuscatus breeding  1,100,000 breeding pairs  A4i  Least Concern 
A4iii Species group - waterbirds breeding  2,500,000-4,999,999 individuals  unknown  A4iii   
A4iii Species group - seabirds breeding  20,000-49,999 individuals  unknown  A4iii   

Land use

Land-use Extent (% of site)
not utilised -

References Feare (2000), Mortimer (1984), Rocamora and Skerrett (submitted), Rocamora et al. (submitted), Skerrett (1996b, 1999), Stoddart (1984).

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Cosmoledo. Downloaded from on 28/10/2016

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