Justification This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Family/Sub-family Dicruridae

Species name author (Bechstein, 1794)

Taxonomic source(s) Dowsett and Forbes-Watson (1993)

Taxonomic note Dicrurus modestus (Sibley and Monroe 1990, 1993), including the subspecies coracinus from west and central Africa, and the subspecies modestus confined to the island of Príncipe and D. adsimilis (Sibley and Monroe 1990, 1993) were previously treated as D. modestus (a monotypic species confined to Príncipe only) and D. adsimilis (including coracinus) following Collar and Andrew (1988). All are now lumped into D. adsimilis following Dowsett and Forbes-Watson (1993), for a review by the BirdLife Taxonomic Working Group found no precedent or justification in the primary literature for treating modestus as distinct. Adult specimens in the Natural History Museum, Tring are essentially as on the mainland.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

unknown

unset

14,400,000 km²

No

Range & population The subspecies modestus (previously recognised as a separate species), is endemic to the island of Príncipe, São Tomé e Príncipe. Increased use of pesticides would reduce the abundance of its invertebrate prey and might lead to its disappearance from cultivated areas. The number of small farms on Príncipe is increasing as land is privatised, which is in turn leading to a reduction in tree cover. It is not known how this will affect the subspecies.

Ecology: Subspecies modestus is widespread in open and forested habitats, with the exception of primary forest on the central massif, and is commonest in open plantations and in edge habitats (Atkinson et al. 1991, J. Baillie and A. Gascoigne in litt. 2000).

Threats The subspecies modestus could be adversely affected by an increase in the use of pesticides, which would reduce the abundance of its invertebrate prey and might lead to its disappearance from cultivated areas. The number of small farms on Príncipe is increasing as land is privatised, which is in turn leading to a reduction in tree cover. It is not known how this will affect the subspecies.

References Hall and Moreau 1970, Atkinson et al. 1991, Roberts 1993, Zimmerman et al. 1996, Borrow and Demey 2001, Stevenson and Fanshawe 2002

Text account compilers Helen Temple (BirdLife International)

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Dicrurus adsimilis. Downloaded from http://www.birdlife.org on 9/2/2010

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.

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