Crows can vocally count up to four. The intelligent birds recognize and react to numbers in a process similar to that of human cognition, according to a new study.

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.

As children grow older, they begin to map number words to collections of objects, for example, “two socks,” and by age 2, many children can subitize up to three items, and 4- and 5-year-old ...

That makes numbers more tangible and easier to add or subtract. The societies that moved beyond finger-counting did so, argues Overmann, because they developed a clearer social need for numbers.