Image 1 - Pigeons Have Numerical Abilities Just Like Primates
December 23, 2011

Pigeons Have Numerical Abilities Just Like Primates

Researchers at University of Otago in New Zealand have found that pigeons are able to learn abstract rules about numbers, an ability that until now had been demonstrated only in primates.

Scientists had trained rhesus monkeys in the 1990s to look at groups of items on a screen and rank them from lowest number of items to highest. It has already been known that pigeons know how to count, just like many other animals, including bees and other species of birds.

In a study, published in the international journal Science, the researchers from the school´s Department of Psychology showed that pigeons can compare pairs of images picturing up to nine objects and order them from lowest to highest number with a success rate above chance.

Dr. Damian Scarf, lead author of the study, said that up until now, only humans and primates were thought to have the ability to use abstract numerical rules this way. “Our research not only shows that pigeons are also members of this exclusive club, but, somewhat surprisingly, their performance is on a par with that of monkeys,” he said.

For the study, Scarf and his colleagues trained pigeons by presenting them with 35 sets of three images, each with one, two, or three objects of different sizes, shapes and colors. They found the birds were able to correctly pick a card with one large green square first, followed by a card with two small red ovals, and then one showing three long blue rods.

But it didn´t end there. The pigeons also demonstrated a new ability -- faced with two cards each showing up to nine images, they could tell which one had more, which indicated they had an abstract understanding of the single-digit amounts, just like rhesus monkeys.

Elizabeth Brannon, a professor of psychology and neuroscience at Duke University, who worked on the rhesus monkey study in the 90s, said she was impressed by the new results. “Their performance looks just like the monkeys,” she told James Gorman of the New York Times.

“I was surprised,” Dr. Scarf todl Gorman, referring to the pigeons seemingly innate abilities in rules of number abstraction. It is unclear, however, if this ability evolved separately, or if both pigeons and primates share this ability because of an ability that was present in a common ancestor, he and his colleagues noted.

That would be really amazing, because the common ancestor of both pigeons and primates would have lived about 300 million years ago, long before dinosaurs and mammals roamed the earth. Counting may have already been important, but Scarf said he is leaning more toward separate evolution. “I can definitely see why both monkeys and pigeons could profit from this ability,” he said.

It also remains unclear if pigeons can count large numbers since testing only involved single numbers up to nine, wrote the researchers in their paper: “Pigeons on Par with Primates in Numerical Competence.”

While pigeons are obviously nowhere near as capable as humans in abstract counting, the study does show that “an animal with a brain structured quite differently to ours is still able to perform complex mental tasks of which only humans were once thought capable. Our findings add to a growing body of evidence that pigeons are among a number of avian species exhibiting impressive mental abilities that really do give the lie to the old ℠bird brain´ insult,” said Scarf.

The researchers next plan to investigate the neural underpinnings of the pigeons´ numerical abilities by recording their brain cell activity when they undertake numerical tasks. The team also plans to test kea, a New Zealand bird species which has been claimed to have some of the intelligence of a six-year-old child. Scarf plans to utilize two keas and other parrot species that are housed at the Dunedin Botanic Garden aviary in his upcoming studies.


Image 2: Pigeon participating in Dr Scarf's research. Photo by William van der Vliet


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