|D. a. divaricatus in The Gambia and song of nominate subsp., South Africa|
The fork-tailed drongo, also called the common drongo, African drongo, or savanna drongo (Dicrurus adsimilis), is a species of drongo in the family Dicruridae, which are medium-sized passerine birds of the Old World. It is native to the tropics, subtropics and temperate zones of the Afrotropics. Its range was formerly considered to include Asia, but the Asian species is now called the black drongo (Dicrurus macrocercus).
Range and habitat
The fork-tailed drongo is a common and widespread resident breeder in Africa south of the Sahara. These insect-eating birds are usually found in open forests or bush, and are tolerant of arid climates.
The fork-tailed drongo is 25 cm long and has short legs. They are medium sized and usually weigh about 50 grams. Males are mainly glossy black, although their wings are duller. Females are similar but less glossy. It is large-headed with well-developed rictal and nasal bristles, which are used as sensory organs. The rectrices curve outwards, forming the forked tail for which the species is named. The hooked bill is black and heavy, and the eye is red.
The call is a metallic strink-strink. The fork-tailed drongo uses alarm calls to steal food from birds and animals such as meerkats. They make drongo-specific calls as well as mimicked calls. The mimicked calls help them while they target other animals that are eating food. The animals flee, and leave their food. Once they are gone, the drongo steals it.   Vocal at dawn and dusk.
They still-hunt by sitting very upright on a prominent perch, much like a shrike. They are usually solitary and form monogamous breeding pairs. They are aggressive and fearless, regularly mobbing or attacking much larger species, including birds of prey, if their nest or young are threatened or their territory is compromised. They also join mixed foraging bird parties, and will initiate mobbing of common enemies. To maintain their plumage condition they may rain-bathe, foliage-bathe or plunge-dive into water. Terrestrial foragers like babblers may use the drongo as a sentry.
They are almost exclusively carnivorous, but may take nectar when available. They flycatch or take prey from the ground, and are attracted to bush fires. They also utilize disturbance caused by animals, and may perch on their backs. At times they catch ectoparasites on mammals, plunge-dive to catch fish, or kleptoparasitise mammals or birds.
Observations show that the fork-tailed drongo in Africa are capable of using deceptive mimicked alarm calls to steal food from birds like pied babblers and animals such as meerkats. Tom Flower observed that fork-tailed drongos spend a quarter of their time following other animals. Drongos sometimes act as sentries when a predator is approaching, warning their neighbours with genuine alarm calls. But drongos also earn a quarter of their daily calories by sounding a false alarm when another animal finds food. When the meerkats and babblers flee from the non-existent predator, the drongo steals their food. Though in doubt, researchers have considered the possibility that these drongos possess theory of mind, not fully shown in any animal other than humans.
Its populations are genetically highly structured, and four races are accepted. The races D. a. modestus (Príncipe) together with D. a. coracinus and D. a. atactus (Bioko to west and central mainland Africa, from Guinea east to western Kenya and south to Angola) are usually split as a separate species, the velvet-mantled drongo, D. modestus (Hartlaub, 1849).
- D. a. divaricatus (M.H.C.Lichtenstein, 1823)
- D. a. apivorus Clancey, 1976
- D. a. fugax W.K.H.Peters, 1868
- D. a. adsimilis (Bechstein, 1794)
- BirdLife International (2012). "Dicrurus adsimilis". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- Carnaby, Trevor (2008). Beat about the bush: Birds (1st ed.). Johannesburg: Jacana. pp. 572–573. ISBN 9781770092419.
- Flower, Tom (May 22 2011). "Fork-tailed drongos use deceptive mimicked alarm calls to steal food". PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES. 278 (1711). Check date values in:
- Flower, Tom (2010). "Fork-tailed drongos use deceptive mimicked alarm calls to steal food". Proceedings of the Royal Society B. doi:10.1098/rspb.2010.1932. PMC 3081750.
- Rocamora, G.; Yeatman-Berthelot, D. (2016). "Fork-tailed Drongo (Dicrurus adsimilis)". Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. Retrieved 24 August 2016.
- Yong, Ed (1 May 2014). "The Bird That Cries Wolf Changes Its Lies". National geographic. Retrieved 2 May 2014.
- Flower, T. P. (2014). "Deception by Flexible Alarm Mimicry in an African Bird". Science. 344 (6183): 513–516. doi:10.1126/science.1249723. PMID 24786078.(subscription required)
- Flower, Tom (May 2015). "Dual parasitism of Fork-tailed Drongos by African and Jacobin Cuckoos". OSTRICH. 86 (1–2). Check date values in:
- Bowie, Rauri; Crowe, Tim; Voelker, Gary; et al. "Comparative phylogeography of southern African birds" (PDF). Annual Report January – December 2009, Research Programmes & Initiatives: Systematics and Biogeography. Percy FitzPatrick Institute, University of Cape Town. Retrieved 24 August 2016.
- Chittenden, H.; et al. (2012). Roberts geographic variation of southern African birds. Cape Town: JVBBF. pp. 204–205. ISBN 978-1-920602-00-0.
- African Bird Club (2006) ABC African Checklist: Passerines. Accessed 16/01/08.
- Birds of The Gambia by Barlow, Wacher and Disley, ISBN 1-873403-32-1
- Sinclair, Ian & Ryan, Peter (2003) Birds of Africa south of the Sahara, Struik, Cape Town.
- Fuchs, J.; De Swardt, D.H.; Oatley, G.; Fjeldså, J.; Bowie, R.C.K. (2018). "Habitat- driven diversification, hybridization and cryptic diversity in the Fork- tailed Drongo (Passeriformes: Dicruridae: Dicrurus adsimilis)". Zoologica Scripta: 1–19. doi:10.1111/zsc.12274.
|Wikimedia Commons has media related to Dicrurus adsimilis.|
- Fork-tailed Drongo - Species text in The Atlas of Southern African Birds.
- Fork-tailed drongo videos, photos & sounds on the Internet Bird Collection