"Birdbrains" should not be ignored in studying the evolution of g

The authors evaluate evidence for general intelligence (g) in nonhumans but lean heavily toward mammalian data. They mention, but do not discuss in detail, evidence for g in nonmammalian species, for which substantive material exists. I refer to a number of avian studies, particularly in corvids and parrots, which would add breadth to the material presented in the target article.