Friend or foe, ravens recognize you

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Friend or foe, ravens recognize you

Updated: April 28, 2012 - 4:29 PM

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A raven, in an undated handout photo. A study in Europe finds that after a separation of three years, ravens that once lived as a group recognized the recorded calls of their former friends or foes.

Photo: Cyril Russo, New York Times

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Ravens have the ability to recognize old friends and react negatively to seeing a foe, said a study in the journal Current Biology. Marcus Bockle, a University of Vienna zoologist, and his team describe a group of 12 ravens kept together for three years, then separated. Three years later, they recorded them and played their calls to one another. "If they heard a friend, then they called out in a friendly voice," he said, opposed to an unfriendly (deeper and elongated) voice.

NEW YORK TIMES

Birds are famously good navigators. Some migrate thousands of miles, flying day and night, even when the stars are obscured. Scientists have known that one navigational skill they employ is an ability to detect variations in Earth's magnetic field. How this magnetic sense works, however, has been frustratingly difficult to figure out. Now, researchers at Baylor College of Medicine, Le-Qing Wu and David Dickman, have solved a central part of that puzzle, identifying cells in the brain of pigeons -- the earliest form of e-mail -- that record detailed information on Earth's magnetic field, a kind of biological compass. Navigating by magnetism includes several steps, said the report in Science Express. Birds have to have a way to detect a magnetic field, and some part of the brain has to register that information; it seems likely that another part of the brain then compares the incoming information to a stored map. The researchers identified a group of cells in the brain stem that record both the direction and the strength of the magnetic field. And they have good, but not conclusive, evidence to suggest that the information these cells are recording is coming from the bird's inner ear. A well-known and often-mentioned study of London taxi drivers showed that experienced drivers with a mental map of London had a hippocampus larger in one area than people without their experience. In some birds that hide seeds and return later to their caches with astonishing accuracy, the hippocampus grows and shrinks seasonally, presumably as they map their hiding spots. NEWS SERVICES