Credit: WILLIAM LEAMAN/ALAMY

Whatever the type of danger, crows defend themselves in the same way: by mob attack. But the brain circuitry behind the behaviour seems to differ.

John Marzluff at the University of Washington in Seattle and his colleagues caught and caged American crows (Corvus brachyrhynchos, pictured) and showed them various types of threat. The researchers then imaged the crows' brains, looking for changes in activity in areas of the brain that process emotion, memory and movement.

Different brain areas were activated depending on whether the crows were exposed to an innate threat (a taxidermy hawk), a known human threat (the person who had initially captured them) or a potential threat (an unknown person holding a dead crow). The researchers suggest that mobbing behaviour could be guided by distinct neural circuits involved in innate responses, memory and learning.

Proc. R. Soc. B 280, 20131046 (2013)