Aug. 28 (UPI) -- Crows don't call involuntarily. According to a new study, the birds have conscious control over the release and onset of their vocalizations.
Previous studies have highlighted the abilities of songbirds to adapt complex songs. The flexibility of songbird vocalizations suggested the performances are under cognitive control, but scientists couldn't be certain.
Researchers at the University of Tübingen in Germany devised a series of experiments to prove crows can release or withhold their vocal calls at will -- that the birds don't simply reflexively vocalize in response to food, mates or predators.
For the first part of the "detection task," three male carrion crows were trained to release calls in response to a visual cue of colored squares. The crows were also trained to withhold calls in response to a different cue. Two of the three crows were trained with different colored cues than the third.
All three crows were shown the "go cues," the cue to call, at precise intervals of time. Even when food was presented as a reward, the birds learned to withhold their calls when a "no-go cue" was presented.
While the simple tests showed crows exercise cognitive control over their calls, the researchers acknowledged more work is needed to identify the neural mechanisms behind the control of vocalizations.
Researchers published their work this week in the journal PLOS Biology.
"Our study shows that crows can be taught to control their vocalizations, just like primates can, and that their vocalizations are not just a reflexive response," they said in a news release. "This finding not only demonstrates once again the cognitive sophistication of the birds of the crow family. It also advances our understanding of the evolution of vocal control."