Figure 1. A Fork-tailed Drongo Bird.
Fork-tailed Drongo birds in Africa have evolved a very interesting and intelligent way of getting food. They are able to mimic the calls of other species, like birds and even meerkats. So when they are feeling a bit hungry and spot another animal with a tasty morsel, they cleverly mimic the alarm calls of that animal then retrieve the food when it is left behind by that animal running for its life. Ornithologists already knew the skilled vocal thieves were able to mimic other animal's alarm calls, however they wanted to know how the species kept their victims from habituating to their deceptive behavior. So they spent more than 800 hours in the field, watching 64 Drongo birds and recording their calls and behaviors. Through this, the researchers witnessed around 700 attempted food robberies. They realized, after analyzing their data, that the Drongo's success is actually quite complicated. These birds are able to produce a large number of mimicked alarm calls, some individuals had a repertoire of up to 30 calls! Six of these alarm calls are used within their own species, which other animals pick up and use the birds as their own personal bodyguards warning them of danger. Throughout the day, Drongos will pick a victim and then report a number of truths and lies, warning the individual of real and fake predators while also switching between their own species warning calls and mimicked ones. To figure out how effective this system was, researchers played a number of different alarms to a species of Pied babblers that are often a target species for the Drongos. They played drongo alarms, drongo-mimicking-babbler alarms, true babbler alarms and warning calls from starlings. The Pied Babblers reacted to their own species warning calls the most but also reacted to the Drongos warning calls as well, just not as frequently. By mixing up which species to victimize, the Drongos have quite an intelligent and successful system until the species becomes aware of what these sneaky birds are up to. Although this example is not necessarily in the realm of cognition, it sure sparks an interesting idea of how the Fork-tailed Drongo bird learns other species alarm calls and is able to judge just exactly when to use the call.
Figure 2. A Pied Babbler.
References:
Nuwer, R 2014, 'This bird tricks other animals into handing over their meals', Smithsonian.
Drongos are also notorious for harassing other birds substantially larger than them! I have seen them chasing away eagles and smaller birds of prey. Has any study looked at how these birds learn and how/when they are able to switch vocalisations in a given context? Some birds have a great ability to mimic, while others don’t, so I’m just wondering what makes the drongo so good at it? Any ideas?
ReplyDeleteHello Tasmin! I believe it may be something that is learned from other drongo birds (perhaps the parents?) as well as practice. The researchers saw hundreds of attempted food robberies during their study so I can't imagine how many robberies a single drongo bird attempts in their life. I also believe the actual ability to mimic would just be an evolutionary survival method for getting food. I am not sure of any studies that have looked at this however these are just my ideas of how this has evolved.
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