Self-Controlled Crows Ace the Marshmallow Test
By Jyoti Madhusoodanan

Are four treats better than two? Not if you’re a crow picking a favorite snack.

Crows and ravens hold off on gobbling a tidbit when they can see a better one coming after a short wait. But they’ll only act with restraint if the future treat is something they like more than what they already have, not if it’s just more of the same.

The new results, published in the April 2014 issue of the journal Animal Behavior, suggest the birds aren’t just capable of controlling their impulses, they also choose when to give in to temptation. The experiments mimic the classic test where kids and adults are left alone with a marshmallow, and promised a better treat if they refrain from biting in. Like many children and adults, crows and ravens waited.

To test the birds’ patience, researchers began by learning their favorite foods. They offered members of the corvid family — seven crows and five ravens — bits of bread, grapes, sausage or fried pork fat and other treats, and noted each bird’s preferences. In a series of subsequent tests, each bird was offered a food item. After delays ranging from a few seconds to ten minutes, they could exchange it for a treat they liked more (sausage and fried pork fat were high on all the birds’ lists), or return it for a larger helping of the same snack.

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