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Bird brains are tiny - the common pigeon's is about the size of a peanut. But having smaller noggins doesn't mean birds are unintelligent. One way scientists estimate brain power is through the number of neurons present. Some birds have upwards of 1-2 billion - similar to monkeys. The intelligence of birds - from New Zealand parrots that understand probability, to ravens that can plan for the future - isn't a surprise to researchers who have long seen their capabilities. Early models proposed that only a small region of bird brains was responsible for complex behaviors, but this has been revised in recent years. Still, the detailed, internal organization of bird brains hadn't been explored until now. Two new studies in Science dig into their structure and function, revealing even greater similarities to mammalian brains. Researchers shined different angles of light into extremely thin slices of the pallium, the area of bird brains with a similar function to the neocortex of mammals. This allowed them to see a 3D view of the fibers that connect neurons. The fibers of owls and pigeons were organized much like those of mammals: parallel fibers along the pallium were crosscut by perpendicular fibers between layers, forming columns of connection. These microcircuits could explain how birds are capable of complex behaviors.