Fork-tailed Drongos: Marvelous Mimics
A recent study by evolutionary biologist Tom Flower of the University of Cape Town in South Africa has revealed that the African fork-tailed drongo mimics alarm calls of other species as part of its food gathering strategy. Wildlife observers in Africa have noted that the drongo is an accomplished thief, but it was thought that it was using its own alarm call to falsely alert other birds and meerkats that a predator was nearby, thereby causing them to drop their meal, which the drongo would swoop in and claim. It is estimated that the drongo steals more than twenty percent of its daily food. But the lengthy study carried out by Flower in the Kuruman River Reserve, located in the Kalahari Desert, yielded some astounding insight into the drongo’s ability to perfectly mimic a variety of bird and mammal species for its own advantage.
In the wild, birds and mammals often pay attention to other species in their environment when it comes to sounding the alarm. An extra pair of eyes and ears can be handy when it comes to safety. But as researchers have discovered, the drongo can’t be trusted. Perched high up in a tree a drongo watches with keen interest as meerkats forage, and when one of them catches something, an insect or lizard, the drongo sounds its own alarm call, anticipating that the meerkat will drop its prey and head for cover. However, the foraging meerkats are likely to ignore the drongo after it has used its own alarm call a few times. Undaunted, the drongo will switch to the alarm call of another bird species, often with successful results.
During the study, Flower and his colleagues tracked and recorded the calls of 42 drongos as they attempted to steal food from the same target. It was noted that of the 151 recorded incidents, the drongos switched to a different alarm call a total of 74 times. After giving its own alarm call without success, a drongo may give the alarm call of its target, which general proved successful.
Flower notes that he doubts the birds have ‘theory of mind’ – the ability to understand that another being has different beliefs and intentions – which is currently only attributable to humans. It’s more likely that they are responding to feedback, or have an ability to grasp cause and effect, and use this to their advantage. Nonetheless, this is another example of the keen intelligence of the feathered creatures that share our planet.