Bird brain? Ounce for ounce birds have significantly more neurons in their brains than mammals or primates
The first study to systematically measure the number of neurons in the brains of birds has found that they have significantly more neurons packed into their small brains than are stuffed into mammalian and even primate brains of the same mass. Ref. Source 2a.
Speaking for bird intelligence the crow is the bird that comes to mind when using tools. For me that is a bird that uses intelligence to say the least. We as humans only use 10% at most of our brain power, so what if birds were using all of theirs?. Would it be like in the alfred hitchcock's movie "The Byrds". You can see crows using tools to get to food and even some crow make modified tools to get whatever they are after. So the next time that you throw a rock to scare off a murder of crows, don't be surprised one day that they will perhaps throw it back.
That 10% thing is a particularly egregious myth. If your brain is properly functioning, every single synapse in it has a function and is being used.
Human brains can be, and are under utilized, but improving that is a matter of stimulating new neural connections, not sparking up unused grey matter that's just somehow sitting there, and people are certainly not operating anywhere near 90% below peak.
Edited: daishain on 1st Dec, 2016 - 4:31am
I don't know if this finch story depicts intelligence but it is cool. I am not surprised if there are more neurons in bird brains than mammals for decision making. I imagine that flying at high speeds in a world full of obstacles, predators, and prey requires a lot of snap decisions.