An African bird is an accomplished impressionist, scientists say. Mimicking distress and alarm sounds of other animals to trick them into abandoning their food, which the bird then claims as its own.
The fork-tailed drongo, which lives in the Kalahari Desert, not only can copy calls of distress of several other birds species but can give a pretty good imitation of the alarm cry of meerkats, the researchers found.
South African ornithologist and evolutional biologist Tom Flower has recorded the sounds in a portion of the Kalahari in his country's Kuruman River Reserve.
Flower, in a study published in the journal Science, reports recording 688 instances of a drongo attempting to filch food from other species.
Their larcenous repertoire of sounds included six alarm calls specific to drongos along with an additional 45 calls accurately mimicking alarm sounds of other species, Flower and his colleagues reported.
Varying the choice of alarm calls improved the food-pilfering success rate of the robin-sized birds.
"Drongos were more likely to change the type of false alarm call when their previous food-theft attempt failed," researchers said.
While other species of birds and meerkats benefit by having drongos in the area -- they don't need to remain as vigilant and are able to spend more time in foraging while the birds keep watch for predators -- they pay the price in the occasional lost meal when a drongo decides to switch from an honest alarm call to one intended to deceive.
A drongo can secure almost a quarter of its daily food needs by raising false alarms and then making off with a victim's meal. Having more than one weapon in their arsenal of dishonest calls improves their success rate.
"The drongos are producing their calls tactically. They're changing their calls in response to the feedback they get from their target," Flower says. "And that's how they're able to overcome the problem of crying wolf too often."
The tactic works because many species will pay close attention to other animals' warning calls and learn to recognize them, Flowers says.
While birds like mynahs and parrots can mimic mammal sounds, including human speech, it's unsure what benefit they might gain from such ability, he says.
"The reason drongos are special is that we don't know why most species mimic vocalizations, while drongos use mimicry to improve their deception payoffs."
