Justification of Red List Category
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.
The global population size has not been quantified, but it is believed to be large as the species is described as common in at least parts of its range (Hall and Moreau 1970, Roberts 1993, Zimmerman et al. 1996, Borrow and Demey 2001, Stevenson and Fanshawe 2002). The subspecies modestus (previously recognised as a separate species), was considered Near Threatened, although its population size is unknown numbers are assumed to be small.
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.
Dicrucus adsimilis has a very large range extending from Mauritania, Senegambia and Guinea east in savanna belt to northern Cameroon, southern Chad, central and southern Sudan, Ethiopia, Eritrea and Somalia, south to Central African Republic, The Democratic Republic of the Congo, Congo, Uganda, Kenya, Tanzania, Gabon, Angola, Zambia, Malawi, Mozambique, Zimbabwe, Namibia, Botswana, South Africa, Swaziland and Lesotho
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).
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.
Text account compilers
Derhé, M. & Temple, H.
BirdLife International (2018) Species factsheet: Dicrurus adsimilis. Downloaded from http://www.birdlife.org on 15/12/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 15/12/2018.