A study out Monday in the journal Current Biology found that pigeons are able to judge time and space, much the way humans and apes can.
The report is the latest to show that so-called lower-order animals such as birds, reptiles and fish are capable of intelligent decision-making.
“Indeed, the cognitive prowess of birds is now deemed to be ever closer to that of both human and nonhuman primates,” said study author Edward Wasserman, professor of experimental psychology at the University of Iowa.
“Those avian nervous systems are capable of far greater achievements than the pejorative term ‘bird brain’ would suggest.”
Birds were shown a computer screen on which a horizontal line appeared for either two or eight seconds.
Sometimes the line was 9.5 inches (24 centimeters) long; other times it was two inches (five centimeters).
Pigeons could peck one of four visual symbols to indicate if the line they saw was long or short, or if it appeared briefly or for a long time. The correct answer earned them food.
Researchers then made the task more complicated, introducing more line lengths and making the test vary so pigeons could be tested at random on either space or time.
“Pigeons judged longer lines to also have longer duration and judged lines longer in duration to also be longer in length,” said the report.
Experiments on humans and monkeys have shown similar results.
But the area of the brain in humans where this processing takes place — the parietal cortex — does not appear to exist in pigeons.
That suggests complex processing takes place in another part of the bird brain.
“The cortex is not unique to judging space and time,” said co-author Benjamin De Corte, a graduate student with the university’s Iowa’s Neuroscience Institute.
“The pigeons have other brain systems that allow them to perceive these dimensions.”