This tale from Alex Wild at Myrmecos.net is absolutely amazing, with stunning photographs to boot. He found a population of flies that were habitually “mugging” ants – seizing them and forcing them to regurgitate food. This kind of behaviour is known as kleptoparasitism – a word with the same Greek roots as kleptomaniac.
The flies have discovered how to mimic a signal the ants use among themselves, by touching each others’ palps. This signal normally stimulates regurgitation from one ant to another. The ants aren’t clever enough to work out that the signal is not coming from another ant, so they happily give up the food. Fantastic. The paper just came out in African Invertebrates.
This struck me as very similar to this paper in Proceedings B by a friend, Tom Flower, who studies fork-tailed drongos – South African birds that are also kleptoparasites. They are very good at mimicking other animals’ calls. The drongo will follow a group of feeding animals (meerkats, for example) and wait until one has a juicy piece of food – and then will bark out a mimicked meerkat alarm call so that the feeding meerkats drop their food and run for cover. The drongo then swoops in and steals the food. Very clever!
In both cases the thief is exploiting a response by the victim that usually helps it – in the ants’ case, distributing food around the colony; in the meerkat’s case, fleeing from potential danger. Thieves are usually so rare that it is not worth being suspicious. But, just like the “boy who cried wolf”, the more common the thieves become, the less likely this tactic is to succeed. The more times a victim is deceived, the more it becomes worthwhile for the victim to take the effort to work out whether the next signal is real.
However, neither of these cases is likely to be a case of “tactical deception” in that the animals probably do not understand or knowingly manipulate the mental states of their victims. That kind of behaviour occurs in primates, though: examples are on record of baboon babies screaming for their mother as if attacked when they see fellow troopmates passing by with food. After the mother chases off the “attacker”, who drops the food as a result, the infants eat it. We are still waiting for an insect example of this level of trickery!