Around 68 percent of the young birds headed towards the relation that they had seen before. If they had imprinted on one identical pair of objects, they were more likely to prefer a second identical pair over a different one. But if they imprinted on mismatched objects, they preferred other mismatched pairs over identical ones. “Their brains are accumulating a catalog of properties that could apply to other objects,” says Kacelnik.

Do all bird brains pattern match this way or just ducklings?