|D. a. fugax pictured in Rwanda, and song of nom. subspecies, South Africa|
The fork-tailed drongo (Dicrurus adsimilis), also called the common drongo, African drongo or savanna drongo, is a small bird that can be found in a very substantial range, from the Sahel to South Africa, excepting the Congolian rainforests and Upper Guinean forests. They are a passerine, part of the family, Dicruridae, with four recognized subspecies. Physically this species is characterized with a narrow fork-shaped tail, red-brownish eyes, and black plumage throughout all of his body. As an omnivorous species, its diet consists of small insects, composing of butterflies, grasshoppers and beetles, besides fruit, including those of Azadirachta indica and Moringa oleifera.
The fork-tailed drongo is known for his ability to deceptively mimic other bird alarm calls in order for a certain animal to flee the scene so he can steal their food (kleptoparasitism). They are also notorious for displaying an aggressive and fearless behaviour by attacking and chasing off much larges animals, including birds of prey. When their nest or young are threatened. Due to his extensive range and stable population, the fork-tailed drongo is classified by the IUCN Red List as an least-concern species.
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. apivorus Clancey, 1976
- D. a. fugax W.K.H.Peters, 1868
- D. a. adsimilis (Bechstein, 1794)
- D. a. jubaensis van Someren, 1931
- Range: Ethiopia, Eritrea, and Somalia
Distribution 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. Its range was formerly considered to include Asia, but the Asian species is now called the black drongo (Dicrurus macrocercus).
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 behind. 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.
Two to four eggs are laid in a cup nest in a fork high in a tree. Drongos are commonly used as brood hosts for the African cuckoos (21.8% of nests), in the Kalahari Desert was found that Jacobin cuckoos also parasite the drongo.
- BirdLife International (2016). "Dicrurus adsimilis". IUCN Red List of Threatened Species. 2016: e.T103710902A95034217. doi:10.2305/IUCN.UK.2016-3.RLTS.T103710902A95034217.en. Retrieved 19 November 2021.
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- 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.
- Chittenden, H.; et al. (2012). Roberts geographic variation of southern African birds. Cape Town: JVBBF. pp. 204–205. ISBN 978-1-920602-00-0.
- 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): 1548–1555. doi:10.1098/rspb.2010.1932. PMC 3081750. PMID 21047861.
- Flower, Tom (2010). "Fork-tailed drongos use deceptive mimicked alarm calls to steal food". Proceedings of the Royal Society B. 278 (1711): 1548–1555. doi:10.1098/rspb.2010.1932. PMC 3081750. PMID 21047861.
- 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. S2CID 3005286.(subscription required)
- Flower, Tom (May 2015). "Dual parasitism of Fork-tailed Drongos by African and Jacobin Cuckoos". Ostrich. 86 (1–2): 189–191. doi:10.2989/00306525.2015.1029032. S2CID 84740346.
- 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. 47 (3): 266–284. doi:10.1111/zsc.12274.
- Fork-tailed Drongo - Species text in The Atlas of Southern African Birds.
- Fork-tailed drongo videos, photos & sounds on the Internet Bird Collection