p. 15-16

Many consider learning to be a hallmark of intelligence. It turns out that almost all of the known nine thousand species of birds have a song, but about half of them have to learn how to sing. If they lack the opportunity to learn, they develop songs different from those heard in nature. Young birds must listen to adults, then practice on their own. Birds even appear to practice singing in their dreams. Research shows that sleeping songbirds fire their neurons in intricate patterns similar to those they produce when singing. Some songbirds, like Canaries, change repertoires every year. Scientists correlated this to changes in the birds' brains and went on to find that adult canaries generate a steady stream of new neurons. This overturned a century of scientific theory which held that brains in adult animals do not change. Now it appears that all animals including humans grow neurons throughout their adult lives. On this count, our brains are not so different from those of birds-fortunately.

~Narby, Intelligence in Nature: An Inquiry into Knowledge