Washington, June 9 : A Swedish study from Uppsala University has shown that Siberian jays use over a dozen different calls to communicate the level of danger and predator category to other members of their own group when mobbing predators.

The new study has shown that birds have evolved call systems that are as sophisticated as those of primates and meerkats.

Most prey immediately escape upon detecting a predator. However, when encountering resting predators, many prey approach and mob predators despite the associated risk.

While mobbing predators, prey utter mobbing calls, which have been suggested to vary depending on risk or predator category.

The new study has shown that Siberian jays adjust their mobbing calls depending on both these factors simultaneously.

According to the researchers, both factors are important since they determine the risk posed by the resting predator.

"The chatter of mobbing jays is rather complex. The birds use over a dozen different calls, some of which are specific for owls and other for hawks, the two main predator categories of jays," say researcher Michael Griesser.

Moreover, jays adjust their calling depending on group composition. Family groups utter much more calls than groups that only consist of unrelated individuals.

Together with earlier published findings, this study shows that Siberian jays can possess an extraordinary large "vocabulary" of over 25 different vocalisations, some of which are specific for a situation while others are uttered in various contexts.

"My study supports the idea that the need to survive encounters with predators might have played an important role for the evolution of complex animal communication," says Griesser.

The study is published in the Proceedings of the Royal Society Biological Sciences. (ANI)