Crime pays for Kalahari's feathered con-artist

Drongos use the alarm calls of other animals in order to scare them off, and steal their food according to research.

Dr Tom Flower, a researcher in the Percy Fitzpatrick Institute of African Ornithology at the University of Cape Town, found that not only had the bird figured out how to do this, but it also changes alarm calls when the animals wise up to its shenanigans.

"All the animals in the Kalahari eavesdrop on each other's alarm calls, which provide invaluable information about potential predators. It's a bit of an information superhighway where all the animals speak each other's language," Flower said.

Flower observed the birds' behaviour six days a week for six months a year since 2008 in the Kuruman River Reserve, which is part of the South African Kalahari desert.

"I dread to think how many sand dunes I've climbed, but it was worth it to get the data I needed," Flower said in a statement.

"Because drongos give reliable predator information some of the time, it maintains host responsiveness (of other animals) since they can never know if the drongo is lying or telling the truth," added Amanda Ridley, an evolutionary biologist at the University of Western Australia, another of the researchers.

The scientists noticed that sometimes the other animals "get wise" to the con and ignore repeated false alarm calls. But then the wily drongos simply grab another tool from their toolbox of trickery - they mimic the alarm calls made by other animals, once again conning them into fleeing and leaving their chow behind.

Flower observed drongos mimicking more than 50 calls.

When stealing food from other animals, drongos are able to eat larger prey than they normally would be able to capture on their own like scorpions, beetle larvae and even geckos.

"Crime pays," Flower said, noting that the stolen stuff accounted for about a quarter of the food eaten by the drongos.

"One could argue that the strategy of the drongo to steal food from others seems very dishonourable in human standards. But, yes, if it has found such a crafty way to catch food, which is usually much larger than the food items it catches itself, then we cannot help but admire this clever little bird's adaptiveness," Ridley added.

According to Flower the species in the reserve are quite habituated to humans, which makes them easier to tag for future study.

"We can unravel the interactions between all these animals because different individuals are identifiable by coloured leg bands (in the case of the birds), or L'Oreal hair dye marks on the fur of the meerkats (don't worry, it's been tested on humans)," Flower said.

Flower was so successful at habituating the birds to his presence, that they came when he called them by name.

"So if I want to find drongo 'Dave', for example, I can walk into his territory, give a call and he’ll come flying over to me in return for a mealworm reward. He'll rapidly get back to his natural behaviour, hawking flies or following meerkats and babblers to steal their food, allowing me to tag along and watch what happens," Flower said.

Dr Flower is now following juvenile drongos during their development, to learn more about how they learn the mimicking behaviour.

Source: Crime pays for Kalahari's feathered con-artist (Sunday Times (SA) 12-05-15)