It’s no secret there are some smart bird species out there. Crows are good with human? faces, domestic chickens count numbers from left to right, and cockatoos can pick locks. Bowerbirds even have a knack for sculpture. Now, the pantheon of avian DaVincis might need to make room for one more: a new study suggests pigeons can learn to recognize and categorize objects. Scientists at the University of Iowa taught three pigeons to place 128 different objects into one of 16 categories: car, hat, cracker, duck, baby, key, bottle, cake, fish, flower, pen, phone, dog, plan, shoe, or tree. For example, the birds learned to associate photos of both sneakers and stilettos with the a general symbol for “shoe,” and to group a rose and a lily with the symbol for “flower.” In each test, the birds were shown an object, then offered the choice to peck one of two symbols—one correct, the other not. If they chose right, the subject received a treat. The pigeons, whose brains are no...