By Dr. Becker
Did you know that African fork-tailed drongos (Dicrurus adsimilis) have sticky beaks? It’s true – these birds are straight-up thieves. Fittingly, they belong to a group of animals called kleptoparasites. Kleptoparasites (not to be confused with kleptomaniacs, which are human thieves), routinely steal food caught by other animals.
Drongos Are Gifted Mimics
New research reveals just how clever drongos are at pilfering food. It seems they can mimic the alarm calls of several other species, which causes the other animals to fly or run off, leaving their food stash unattended.
In their native habitat in the Kalahari Desert of southern Africa, the drongos position themselves above ground-foraging birds and small mammals like meerkats, and make alarm calls when they spot danger approaching. The birds or meerkats on the ground respond to the drongos’ calls, and off they go – leaving behind the food they’ve collected.
What’s unique about the drongos, according to a study published in the journal Science,1 is that they give their alarm calls even when there is no danger. When their target species takes off in response to the alarm call, the drongos descend and swipe the food they leave behind.
How Drongos Avoid ‘Crying Wolf’
After awhile, the target species stop responding to a particular false alarm call, so the drongos change it up and mimic other species’ calls to keep the targets on high alert.
According to study co-author Dr. Amanda Ridley of the University of Western Australia:
"Mostly the drongos' alarm signals are honest, but when a target animal finds a particularly large or juicy snack, the drongos may give a false alarm call, causing the [target] to flee and leave their snack behind.”
One of the goals of the study was to prove that animals use deception for their benefit. There are fixed deceptive signals, like the ability of some animals to change body color to camouflage themselves, but drongos are apparently able to alter their deceptive behavior according to circumstance.
The Cleverest Drongos Can Mimic Up to 32 Different Calls
During the course of the study, the researchers observed 64 drongos make just under 700 attempts to steal food from other species. Individual birds were able to vocalize anywhere from 9 to 32 different calls, with 51 different alarm calls recorded in total.
The drongos mimicked the alarm calls of other species for almost half their false alarms, and the birds that used a variety of alarm calls were more successful at not only tricking their targets, but tricking them over and over again. For instance, if a southern pied babbler recognized that a drongo was lying and ignored his alarm call, the drongo changed his approach and started mimicking a starling or another local bird.
As it turns out, the drongos’ ability to mimic the alarm calls of multiple species is a very efficient way to keep their targets spooked.
According to Ridley, the drongos "… recognize the needs of their target species and adjust their strategy accordingly. They have to invest some time in developing the relationship and being seen as a reliable friend, because if they are too dishonest, as is often the case with younger drongos, they are chased away."