When the world admired the boldness and tenacity of Pizza Rat, a rat that went viral after it was filmed dragging a giant slice of pizza down the stairs of a New York City subway station, we implicitly acknowledged that there’s something special about the animals that share our cities.
Scientists had guesses about what that something was—perhaps it had to do with their problem-solving abilities or their fearlessness of people—but they wanted to put it to the test.
A team captured fifty-three Barbados bullfinches from urban and rural sites throughout the island of Barbados. Then, they put the finches through a series of behavioral tests. They tested boldness by observing how long it took the birds to eat seeds after a human disturbance, and neophobia—the fear of new things—by placing unfamiliar objects next to the birds’ food and watching their reactions. The birds were also tested on their problem-solving abilities by having to figure out how to get food out of small drawers and a tunnel, and on skills called acquisition learning, which tests how quickly adaptive behaviors are learned, and reversal learning, which tests behavioral flexibility.
The scientists found that the urban bullfinches were bolder and faster at problem solving than their rural counterparts. However, the urban birds were more afraid of new things, and were no better at acquisition learning or reversal learning than the rural birds. Another difference was that urban birds had enhanced immunity compared to rural birds.