And to continue what oftroy was writing about:

I've read that birds are creative, at least in their song. Avian specialists have noted that birds will listen to each other's song--will imitate the song, learn the song, and then will embellish it: theme and variations in the making.

Our problem as humans is we lack the bird's ear for music. We cannot hear as rapidly as they hear--our human mind works more slowly. When bird song is slowed down so that we can see it in visual representations, that's when the specialists realize what is going on.

So, although the birds may not be able to do what Koko does, they create on a level that neither Koko nor we could compete. The bird's creativity is there--new formations of sound making are made--but they leave us in the dust.