November 30, 2011
Ravens Use Gestures To Signal Potential Partners
Ravens use their beaks and wings to point and hold up objects in order to attract attention, much like humans use our hands to make gestures, according to a new study by German and Austrian experts.
The study is the first time researchers have observed such gestures in the wild by animals other than primates, suggesting that ravens (Corvus corax) may be far more intelligent than previously believed.
Simone Pika from the Max Planck Institute for Ornithology and Thomas Bugnyar from the University of Vienna found that the ravens also use these so-called deictic gestures in order to test the interest of a potential partner, or to strengthen an already existing bond.
Children frequently use distinct gestures -- such as "pointing" ("look here") and "holding up of objects" ("take this") -- to draw the attention of adults to external objects. This typically begins around the age of nine to twelve months, before children utter their first spoken words.
Scientists believe these gestures are based on relatively complex intelligence abilities, and represent the starting point for the use of symbols and therefore also human language. As such, deictic gestures are seen as milestones in the development of human speech.
However, observations of comparable gestures in our closest living relatives, the great apes, are relatively rare. Chimpanzees (Pan troglodytes) in the Kibale National Park in Uganda, for example, use directed scratches to indicate precise spots on their bodies to be groomed.
Deictic gestures thus represent an extremely rare form of communication evolutionarily and have been suggested as confined to primates only. The current study, however, finds that such behavior is not restricted to humans and great apes.
Pika und Bugnyar spent two years investigating the non-vocal behavior of individually marked members of a wild raven community in the Cumberland Wildpark in GrÃ¼nau, Austria.
They observed that the ravens used their beaks to point to objects such as moss, stones and twigs.
These distinct gestures were predominantly aimed at partners of the opposite sex, and resulted in frequent orientation of recipients to the object and the signallers. The ravens subsequently interacted with each other by, for example, billing or joint manipulation of the object.
Pika said the study provided the first evidence that ravens use gestures “to test the interest of a potential partner or to strengthen an already existing bond”.
Ravens are songbirds belonging to the corvid family, which includes crows and magpies, and surpass most other avian species in terms of intelligence.
The birds are characterized by their complex intra-pair communication, relatively long-time periods to form bonds and a high degree of cooperation between partners.
The current study shows that differentiated gestures have particularly evolved in species with a high degree of collaborative abilities.
"Gesture studies have too long focused on communicative skills of primates only,” Pika said.
“The mystery of the origins of human language, however, can only be solved if we look at the bigger picture and also consider the complexity of the communication systems of other animal groups.”
The study was published November 29 in the journal “¨Nature Communications. November 29, 2011.
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