Bonnie is an orangutan who has taught herself how to whistle. Her imitation of a human caretaker is providing scientists with new insight into social learning and the evolution of speech. It's the first time that a non-human primate has been documented mimicking another species' sound without training. Bonnie lives at the Smithsonian National Zoological Park. Her unique talent is discussed in a new paper in the journal Primates by researchers from the Great Ape Trust and their colleagues. The Great Ape Trust site also has video of Bonnie whistling away. From the Great Ape Trust:
Scientists have long known that orangutans copy physical movements of humans, but Bonnie's whistling indicates that the learning capacities of orangutans and other great apes in the auditory domain might be more flexible than previously believed, (Great Ape Trust researcher Serge) Wich said. The behavior goes against the argument that orangutans have no control over their vocalizations and the sounds are purely emotional – that is, an involuntary response to stimuli such as predators.
Bonnie appears to whistle for the sake of making a sound rather than to receive a food reward or some other incentive. If asked to whistle, she is likely to oblige, another indication to scientists that she makes the sound voluntarily.