African bird steals food by imitating warning calls
The forked tailed drongo bird of Africa—quite the trickster—imitates multiple species' warning calls to scare off other animals and steal their food, a study published Thursday revealed.
The birds often use their own danger alert to trick their fellow bird and beast into abandoning a meal, but researchers were puzzled why animals never wise up to the false-warning scheme.
After following 64 drongos over the course of 847 hours, however, the scientists found that the bird can mock up to 51 other bird and mammal alert noises, including the mongoose and jackal.
Because the drongo can imitate so many species' warnings, animals do not get used to the bird's own false alerts, the biologists said in a study that appeared in the journal Science.
When the bird's alert cry is no longer taken seriously, the drongo switches to another species in its repertory, said author Tom Flower, a biologist at the University of Cape Town in South Africa.
The unique gift allows the Drongo, a black bird with a metallic sheen, that weighs between 2.5 and 4.5 ounces (70 to 125 grams), to exceed the normal vocal constraints that generally limit such imitations in nature.
Animals are often capable of recognizing other species' cries of danger.
Flower and his colleagues carried out their studies in the Kuruman River Reserve in the Kalahari Desert, observing the birds during 688 attempts to seize food from their animal neighbors.
© 2014 AFP