letting nature back in

Fork-tailed Drongos are active visitors to our garden. In the summer months they are at their most conspicuous, issuing their jumbled call while perching in trees, sallying forth to hawk insects.

In the 1985 edition of Roberts Birds of South Africa the calls of the Fork-tailed Drongo are rather delightfully described: “Song loud jumble of strident twanging, creaking and rasping sounds like unoiled wooden wagon wheels; imitates other birdcalls; call note single trumpetlike twank or twilling; vocal on moonlit nights”.

Drongos tend to be feisty birds and they can mob raptors and other predatory birds that are in their area. It is not unusual to see a drongo individual or pair flying above a raptor and “bombing” it from above in an effort to drive it away. They can also be aggressive near their nests, even driving away humans who venture too close.

The name “drongo” is taken from the Malagasy name for the Crested Drongo that is endemic to Madagascar, although there is a subspecies in the Comoro Islands. Globally, there are 29 species of drongo in total, and different species occur in Africa, Asia, Australia and some of the offshore islands.

In southern Africa there are two species of drongo, the Fork-tailed Drongo, which occurs over most of southern Africa (except in Namaqualand, much of the Karoo and Lesotho), and the smaller Square-tailed Drongo, which is confined to the south east and the east.

A Fork-tailed Drongo in our garden looking out for insects to hawk, showing off its deeply forked tail and its characteristic red eye

The Afrikaans name for this bird is Mikstertbyvanger, which means literally fork-tailed bee catcher, an aptly descriptive name, as these agile birds are skilled at hawking insects on the wing, and they have a particular fondness for bees. Fork-tailed Drongos are known for perching nearby to beehives to catch bees returning to the nest.

In addition to eating insects, caught both on the wing and on the ground, Fork-tailed Drongos are also known to eat insect larvae, to catch and eat small birds and lizards, to plunge to catch small fish and occasionally to eat flower nectar, and they have been observed stealing food items from small mammals such as mongooses and from other species of birds.

A Fork-tailed Drongo perching with freshly caught prey

The practice of stealing prey items that have been caught by other species is known as kleptoparasitism. One technique that Fork-tailed Drongos use when stealing food is to fly in aggressively and attack the target animal so as to rob it of its food.

The other strategy is most interesting – the Drongo uses deceit. Many species benefit from the alarm calls of other species in the vicinity, sometimes even seeking out the more aggressive and vocal species for “protection”. The Fork-tailed Drongo can use this response to its advantage by giving a “false” alarm call from its perch in order to frighten an animal with food to run for cover, dropping its food as it takes fright. The Drongo then flies down from its perch and retrieves the dropped food item.

Not only does the Drongo use its own alarm call to frighten a target animal off its food, but it also mimics the alarm calls of other species of birds to make its strategy even more effective. In an ongoing study in the Kalahari region, Fork-tailed Drongos have been seen targeting Pied Babblers and Suricates (Meerkats), when using deceptive alarm calls that cause a target animal to run for cover abandoning its food item in the process. Interestingly, juvenile Fork-tailed Drongos appear to learn this strategy from observing adult birds (Flower 2010).

In the Kalahari region, Suricates, also known as Meerkats, are a favoured target of Fork-tailed Drongos using deceptive alarm calls to frighten an animal into running for cover and dropping its food in the process, enabling the Drongo to steal its food. This group of Meerkats keeping an alert lookout for predators, I photographed in Mabuasehube in southern Botswana

A juvenile Fork-tailed Drongo watching from a perch in our garden. The pale grey edging on the feathers on its breast, and its brown (not red) eye reveal its juvenile status

 Another juvenile Fork-tailed Drongo photographed in our garden. Although very young, this bird was hunting insects for itself. In addition to the speckled and rather dusky feathers and its brown eye, the rather fleshy gape flange reveals its young age

Fork-tailed Drongos are monogamous and solitary nesters. They make beautiful nests bound with spider web that are slung hammock-like across the horizontal fork of a tree branch. Chicks and fledglings are fed and cared for by both parents.

 Fork-tailed Drongos are handsome birds. In our garden they quite often perch in the same trees as Southern Black Flycatchers, when hawking. They can be distinguished from the slightly smaller flycatchers by the red eye, forked tail and more robust bill with a slight hook

I was fascinated the first time I saw an elaborately scalloped tail of a Fork-tailed Drongo. This photograph was taken in Mabuasehube in southern Botswana, and was the first time I noticed such a tail, and at the time I wondered if it was a different subspecies. It turns out that the bird is in moult, with the new tail feathers growing through before the old feathers have been dropped, and so the tail appears to be double-forked

Sources: Flower T. 2010. Fork-tailed drongos use deceptive mimicked alarm calls to steal food. Proceedings. Biological sciences, 278(1711), 1548–1555. doi:10.1098/rspb.2010.1932. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3081750/; Maclean, Gordon Lindsay. 1985. Roberts Birds of Southern Africa (5th edition). Cape Town: Trustees of the John Voelcker Bird Book Fund; Roberts VII Multimedia PC Edition.  1997-2016 Southern African Birding. For details go to http://www.sabirding.co.za/roberts7/portal.html

Posted by Carol