Ravens can recall faces, sounds years later

Vienna, April 20 (IANS) Just as we remember faces and voices of several individuals, certain birds too can recall faces and sounds after a number of years, says a study.

The study conducted by Markus Boeckle and Thomas Bugnyar, both cognitive biologists from the University of Vienna, shows that the common ravens, found across the northern hemisphere of the globe, have the ability to differentiate individuals based on familiarity.

During the study, the researchers found that in response to calls of formerly known individuals, ravens not only increased the number of calls but also changed their call characteristics depending on whether they heard former "friends" or "foes".

This observation suggests that the birds can remember specific individuals at least for three years, the journal Current Biology reports.

The ability to change call characteristics is especially interesting: In case they hear a "friendly" individual, they respond with a "friendly" call, whereas when listening to a "foe," they exhibit lower frequencies and rougher characteristics, an effect already described for other animal species, according to a university statement.

While it was known that mammals could change their voices based on the relationship they shared with others, the researchers are now able to ascertain for the first time that ravens can also do the same based on the relationship quality.