Pigeons can discriminate Picasso paintings from Monets.
In 1995, Japanese scientists tested the visual abilities of pigeons in an unusual way: They showed the birds paintings by Picasso and Monet (Watanabe et al., 1995). Pigeons were trained to discriminate between photographs of Monet and Picasso paintings. They had no problems doing this. Then they were tested with other pictures by the two artists they had never seen before. Still, the birds had no problem discriminating between the artworks. Fascinatingly, the birds were also able to discriminate between the works of other Cubist artists and other Impressionist artists. This shows that pigeons can categorize complex man-made artworks and even discriminate between two art movements—something even some humans without a background in art history might have problems with.
Pigeons can detect cancer in radiology images.
Another unusual experiment on the amazing visual abilities of pigeons was conducted in 2015: Here, the authors tested whether pigeons were able to discriminate benign from malignant human breast tumors in medical images (Levenson et al., 2015). Human medical professionals go through years of highly specialized training before they can reliably detect cancer. Using food rewards, the birds were trained to discriminate between pictures of malignant and benign tissue samples. Later they were shown novel images from both categories and were still able to discriminate between malignant and benign tissue samples. Thus, although detecting breast cancer in medical images is a task that requires considerable training and is very difficult for inexperienced humans, pigeons showed a remarkable ability to make the correct diagnosis. Of course, no clinic will ever use pigeons in medical diagnostics, but the experiment clearly shows how impressive the visual abilities of these birds are.
Pigeons are on par with primates when it comes to counting.
When asked which group of animals is the most intelligent, most people will probably answer primates, the order of animals that contains apes like chimpanzees and gorillas and monkeys like baboons and macaques. But did you know that the numerical abilities of pigeons are on par with that of primates? In a 2011 study, researchers from the University of Otago in Dunedin, New Zealand, investigated whether pigeons showed the ability to learn abstract numerical rules (Scarf et al., 2011). Many animal species have been shown to be able to discriminate between different numbers, e.g., 2 and 20 food pellets. This is an easy task that even insects like honeybees can solve. However, up to that point only primates had been shown to be able to solve more complex mathematical problems like counting from one to nine. The New Zealand researchers presented the birds with sets of visual figures that always contained one, two, and three objects. The birds were trained to respond to the stimuli in ascending order from one to three. The birds could not only do this task, but a similar task with new stimulus sets containing one to nine objects. Thus, pigeons can count from one to nine, just like monkeys – a task that is impossible for many other species.
Pigeons can recognize words.
An important part of reading is the ability to visually recognize words (orthographic knowledge). In a 2016 study (Scarf et al., 2016), a research team from New Zealand and Germany showed that humans are not the only species with orthographic abilities: Pigeons can be trained to discriminate words from meaningless combinations of letters. Using food rewards, pigeons learned between 26 and 58 words and were able to discriminate them from 7,832 meaningless four-letter combinations. Moreover, the birds were able to discriminate completely new words they had never seen during training from meaningless letter combinations. This shows that the pigeons had a representation of what a word is in their brains – and that the neural bases of reading, a skill thought to be uniquely human, is also present in animal brains decidedly different from ours.
Pigeons have an amazing memory.
When thinking of animals with great memory, most people would probably come up with elephants. But in a German study from 1990 (von Fersen and Güntürkün, 1990), pigeons were trained to memorize 725 random black-and-white visual patterns. The patterns did not share any systematic characteristics, so the pigeons had to memorize them one by one. The animals needed to identify the 100 “positive” patterns from the 625 “negative” patterns to obtain food rewards. This is a memory task so complex that most humans would have trouble with it. Nevertheless, the pigeons had no problems with this complicated task.