The three species mainly feed on the nuts from a few species of palms (notably Acrocomia aculeata, Attalea phalerata, Butia yatay and Syagrus coronata).
Glaucous (from the Latin glaucus, meaning "bluish-grey or green", from the Greek glaukós) is used to describe the pale grey or bluish-green appearance of the surfaces of some plants, as well as in the names of birds, such as the Glaucous Gull (Larus hyperboreus), Glaucous-winged Gull (Larus glaucescens), Glaucous Macaw (Anodorhynchus glaucus), and Glaucous Tanager (Thraupis glaucocolpa).
Its bones are distinct from Amazon parrots as well as from the other medium-sized but geographically distant Lear's Macaw (Anodorhynchus leari) and Blue-throated Macaw (Ara glaucogularis).