FAIRBANKS -- Ravens, which are well-known for outwitting everyone from garbage collectors to rival scavengers, may be even smarter than previously thought.
A new European study reports ravens commonly use gestures -- showing and offering objects to each other such as moss, stones and twigs. Such behavior puts ravens in rare company, making the birds the only non-primate confirmed as using pointing gestures to communicate, according to the study. The study, by Simone Pika and Thomas Bugnyar, was published in the Nov. 30 issue of the scientific journal Nature Communications.
Pika said gesturing skill and other intelligence tests, such as gaze-following and problem solving, show ravens could have cognitive abilities on the same level as great apes.
"We have discovered two distinct gestures in ravens, which might be very similar in function to some referential gestures used by humans," Pika, a researcher with the Germany-based Max Planck Institute for Ornithology, said in an email.
Pika and Bugnyar, who is with the University of Vienna, spent three field seasons in the mountains of Austria observing ravens.
They witnessed 38 social interactions between raven pairs, such as using their beaks to show objects to other ravens, mainly members of the opposite sex.
The objects were clearly being presented so a partner would notice them, the study said, which led to interaction between the birds such as manipulating the object together.
A summary of the study said such behavior is "extremely rare," even among great ape species such as chimpanzees. Rare enough, in fact, that Pika said Bugnyar quickly dismissed the possibility of such behavior in ravens when she asked him about it in 2007.
"He looked at me very perplexed and surprised," Pika wrote in an email. "Then he shook his head and said: No."
A few days later, Bugnyar knocked on Pika's office door with a smile on his face. After watching video clips of ravens playing in the snow, he said they were "doing some really interesting things." That discovery led to their collaboration and the project on raven gestures, Pika said.
The thought that ravens are smarter than most may not be a surprise to many Alaskans. The birds have long been a source of legend among indigenous people of the North, frequently appearing in myths as clever tricksters.
They're also known as remarkably adaptive, thriving in regions from deserts to the arctic. They won't hesitate to tear open a garbage bag in search of food while living in the city, but have been known to follow wolf packs in the wild with the hope of feeding on one of their kills.
Stacia Backensto spent three summers studying ravens around the Prudhoe Bay fields as part of her graduate thesis at the University of Alaska Fairbanks. She was fascinated that ravens had adapted to a land without trees by living in oil field structures -- they'd even use old welding rods to build their nests.
Backensto doesn't recall seeing any gesturing behavior like that described by Pika and Bugnyar, but said it was clear in other ways she was witnessing an intelligent bird.
Backensto trapped ravens as part of her study from 2004 to 2006, but found that task extremely difficult after the first summer. Even ravens she had never witnessed, it seemed, knew who she was and what she was doing.
She resorted to disguising herself as an oil field worker to get a better chance at capturing the birds.
"Ravens that I hadn't had prior experience with, we think they learned from other ravens who I was and they'd react aggressively to me," said Backensto, who works today for the National Park Service. "That, to me, was a pretty obvious sign that I was dealing with a really smart animal."
Gesturing behavior among ravens is part of Inuit and Athabascan lore. Hunters have reported that ravens would call to hunters and dip their wings to point in the direction of distant game animals, knowing they would get a free meal if the hunter had a successful kill.
In his book, "Mind of the Raven," biologist Bernd Heinrich reported seeing behavior similar to that described in those stories. He saw raven pairs that would occasionally dip their wings, possibly to "point," accompanied by a glug-glug-glug call.
"It suggests other people have been aware of this behavior before anyone decided to study it," Backensto said.
Pika said they didn't see any pointing behavior as part of their study in Austria, but plan to continue their work to try to determine the meaning and function of various gestures.
The newly published study "represents only the beginning of our investigations," Pika said, "and the more we know the more we do not know."