Instead of an insult, perhaps the phrase "bird-brained" should be a compliment. Particularly if the brain in question belongs to a Goffin cockatoo, a.k.a. Cacatua goffini.
Captive Goffin cockatoos have been observed making and using tools to solve tricky problems. And now a series of experiments has shown that the birds can learn how to make and use the tools simply by watching other cockatoos.