Several vertebrate species can distinguish between, say, two and five bananas—but with the exception of primates, they can’t grasp the numerical rules that would let them arrange their piles of fruit from least to most. Now, new research suggests that pigeons, like primates, can follow these abstract numerical rules. The study is in the journal Science. [Damian Scarf, Harlene Hayne and Michael Colombo, "Pigeons on Par with Primates in Numerical Competence"]
Researchers trained pigeons with cards on which were pictures of one, two or three shapes, sometimes in different sizes and colors. The birds were ultimately able to correctly pick a card with one large green square first, followed by a card with two small red ovals, followed by one showing three long blue rods.
Then, the pigeons demonstrated a new ability—faced with two cards each showing up to nine images, they could tell which card had more. Which indicates that they had an abstract understanding of the single-digit amounts. Rhesus monkeys trained in a similar way displayed the same talents. Whether this shared ability evolved independently or came from a common ancestor is unclear. But it is clear that birdbrains aren’t so dumb.
[The above text is a transcript of this podcast.]