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Aldabra Drongo Dicrurus aldabranus

Justification
This species is listed as Near Threatened because it has a very small population, which occupies a small range. The species is threatened by introduced and native predators. However, there is no evidence of a decline in the population at present.

Taxonomic source(s)
Dowsett, R. J.; Forbes-Watson, A. D. 1993. Checklist of birds of the Afrotropical and Malagasy regions. Tauraco Press, Li
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Distribution and population
Dicrurus aldabranus is found on all four main islands of the Aldabra atoll and neighbouring islets, Seychelles (Penny 1974, G. Rocamora in litt. 2008), and also on the larger lagoon islands of Ile Esprit (where breeding has been reported), Ile Moustique, Gros Ilot, Ile Michel and Ile aux Cèdres (A. Skerrett in litt. 1999, G. Rocamora in litt. 2008). Its extent of occurrence is less than 150 km2 (Stoddart and Westoll 1979). In 1983, the total population was estimated at c.1,500 individuals. It is widely distributed but generally uncommon (Stoddart and Westoll 1979).

Population justification
In 1983, the total population was estimated to number c.1,500 individuals, equivalent to c.1,000 mature individuals.

Ecology
This species frequents mixed scrub, mangroves and Casuarina coastal forest (Penny 1974, Stoddart and Westoll 1979, Threadgold and Johnson 1999, G. Rocamora in litt. 2008), but prefers to breed in the latter two habitats, perhaps because the taller trees provide better nesting sites (G. Rocamora in litt. 2008). Territory size ranges from 2.25 ha in Casuarina woodland to 4.5 ha in mixed scrub (G. Rocamora in litt. 2008). It feeds mainly on a variety of insects and small vertebrates such as geckos. Breeding has been recorded between October-November and March-May, and is timed to coincide with the rainy season from December to March. Its nest, in which 1-3 eggs are laid, is a perfectly round cup made from intertwined fine plant fibres bound with spider webs, situated in a fork near the end of a thin horizontal branch, usually 2-8 m above the ground. The species usually nests in tall trees such as Casuarina and mangroves (e.g. Rhizophora mucronata), but also in Ficus spp. in scrub. The incubation period is 16-18 days, followed by a fledging period of 15-19 days. Juvenile birds are dependent for at least several weeks after fledging, and then remain with their parents until at least the following breeding season (G. Rocamora in litt. 2008).

Threats
It has a high rate of nest failure, probably largely due to introduced predators (G. Rocamora in litt. 2008). Up to 8/10 studied nests are predated at the egg stage, mainly by crows Corvus spp., rats and bulbuls (Pycnonotidae), as observed or suggested by artificial nest experiments (G. Rocamora in litt. 2008). There are no known threats to its habitat, but its small range and population put it at risk from catastrophic events, such as disease or cyclones (G. Rocamora in litt. 2008).

Conservation Actions Underway
Aldabra is protected as a nature reserve under Seychelles legislation (G. Rocamora in litt. 2008). Conservation Actions Proposed
Conduct surveys to obtain an up-to-date population estimate. Monitor population trends through regular surveys. Eradicate introduced predators (G. Rocamora in litt. 2008) and exclude native predators from nest-sites. Protect additional habitat on other islands and islets.

References
Penny, M. 1974. The birds of Seychelles and the outlying islands. Collins, London.

Stoddart, D. R.; Westoll, T. S. 1979. The terrestrial ecology of Aldabra. The Royal Society, London.

Threadgold, R.; Johnson, S. 1999. Aldabra Drongo observation study.

Further web sources of information
Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
O'Brien, A., Pilgrim, J., Robertson, P., Symes, A., Taylor, J.

Contributors
Rocamora, G., Skerrett, A.

IUCN Red List evaluators
Butchart, S., Taylor, J.

Recommended citation
BirdLife International (2014) Species factsheet: Dicrurus aldabranus. Downloaded from http://www.birdlife.org on 25/07/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/07/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Aldabra drongo (Dicrurus aldabranus) 0

Key facts
Current IUCN Red List category Near Threatened
Family Dicruridae (Drongos)
Species name author (Ridgway, 1893)
Population size 1000 mature individuals
Population trend Stable
Distribution size (breeding/resident) 160 km2
Country endemic? Yes
Links to further information
- Additional Information on this species