It used to be thought birds were stupid because their brains were so small relative to mammal brains, and neuronal organisation quite different. Now, it's understood birds are as intelligent as most mammals, because their brains, though small, are densely packed with neurons and glia, which gives them the power to rapidly analyse and react to sensory input, and reason their way through problems on a par with even young humans. Who's to say what a million neurons, also pretty densely packed due to the very small space they have to work with, are capable of? The brain evolves what each species needs to master their physical and social environment -- perhaps bees have already mastered quantum physics!