In a 2017 Current Biology study, researchers showed captive pigeons a series of digital lines on a computer screen for either two or eight seconds. Some lines were short, measuring about 2.3 inches across; others were four times longer. The pigeons were trained to evaluate either the length of the line or how long it was displayed. They found that the more time a line was displayed, the longer in length the pigeon judged it to be. The reverse was true too: If the pigeons encountered a longer line, they thought it existed in time for a greater duration. Pigeons, the scientists concluded, understand the concepts of both time and space; the researchers noted "similar results have been found with humans and other primates."

It's thought that humans process those concepts with a brain region called the parietal cortex; pigeon brains lack that cortex, so they must have a different way of judging space and time.