Pigeons fly in the sky in Sanliurfa, Turkey, December 10, 2016. REUTERS/Umit Bektas Share Tech & Science Birds Animals Animal intelligence The humble pigeon, our urban counterpart, has proven through decades of experiments that it is capable of complex thought. Now, scientists have shown that these "rats with wings" can even understand abstract concepts like space and time. According to research published in the journal Current Biology, pigeons can be trained to differentiate between long and short objects, as well as long and short amounts of time. Researchers at the University of Iowa put short and long lines on a screen and left them on the screen for short and long amounts of time. They showed these lines to pigeons to test how the birds interpreted their differences.  Keep up with this story and more by subscribing now The pigeons signaled to the scientists by pecking on a symbol that represented short or long. If they pecked the right symbol, the scientists  rewarded them with food. The researchers then worked up to more complex tests, showing the pigeons lines of a variety of different lengths, and for various amounts of time. The researchers even surprised the pigeons by testing them sometimes on the length of the line, and sometimes on the amount of time each line was shown. The pigeons had to remember both qualities at the same time, because they didn’t know which one they were about to be tested on. In the end, the pigeons' results showed they were as good at playing the game as primates are. Pigeons fly in the sky in Sanliurfa, Turkey, December 10, 2016. REUTERS/Umit Bektas Pigeon intelligence has been measured in a wide variety of experiments. They are known to be able to switch between tasks better than humans, they can recognize human faces and they can even be taught to discriminate between Monet and Picasso paintings. These findings are particularly surprising because birds lack a parietal cortex, or at least one big enough to notice. The parietal cortex is part of the brain that, in mammals, translates abstract thought. However, we now know that these complex tasks can be learned without a big, mammalian parietal cortex. So next