Broad-billed parrot sketch actually shows that the wings are not particularly short. They appear broad, as they commonly are in forest-adapted species, and the alula appears large, a feature of slow-flying birds. Its sternal keel was reduced, but not enough to prevent flight, as the adept flying "Cyanoramphus" parrots also have reduced keels, and even the flightless kakapo, with its vestigial keel, is capable of gliding. Furthermore, Hoffman's account states that it could fly, albeit with difficulty, and the first published illustration shows the bird on top of a tree, an improbable position for a flightless bird. The broad-billed parrot may have
Kakapo birds. Breeding occurs only in years when trees mast (fruit heavily), providing a plentiful food supply. Rimu mast occurs only every three to five years, so in rimu-dominant forests, such as those on Whenua Hou, kakapo breeding occurs as infrequently. Another aspect of the kakapo's breeding system is that a female can alter the sex ratio of her offspring depending on her condition. A female in good condition produces more male offspring (males have 30%–40% more body weight than females). Females produce offspring biased towards the dispersive sex when competition for resources (such as food) is high and towards the