Math isn't just a human thing. All kinds of animals, from African grey parrots to chimpanzees, are thought to have some kind of mathematical ability, but it can be hard to test. Now, a new study finds ...

Crows can count... out loud! They do so similarly to human toddlers who are learning to tally things up. A neuroscientist trained birds to produce a number of calls in response to random visual cues.