Adaptations of the Alimentary Tracts of Some Australian Lorikeets to a Diet of Pollen and Nectar

Abstract

Lorikeets, which eat mainly nectar and pollen, show a suite of adaptations to this diet not found in granivorous and frugivorous parrots. Lorikeet gizzards are much less muscular, and their intestines shorter, than those of other parrots of the equivalent size. In lorikeets, but not other parrots, the proventricular and pyloric openings of the gizzard lie in the same plane, potentially allowing a rapid transit of both pollen (which is mostly digested in the intestine) and of nectar. Lorikeet tongues differ from other parrot tongues in that they are longer and narrower, with a rougher dorsal surface and a papillate tip. These features may enable lorikeets to harvest more efficiently the pollen so essential to their balanced nutrition.