Observations on pollen harvesting by brush-tongued lorikeets

Abstract

The staple item of diet of Glossopsitta porphyrocephala is pollen. The amount of karri pollen necessary to supply the energy for one bird's basal metabolism of 8.0 kcal/day is supplied by about 500 flowers. The moist papillae on the tongue of the lorikeets enable the birds to collect the dust-like pollen. Less than 1% of the anthers grazed are ingested during the driest months of the year when there is no nectar available. Karri nectar contains sucrose, glucose, fructose, and melibiose and is collected when it flows during the wetter flowering months. It is not a substitute for pollen, which the birds continue to harvest as their source of nitrogen. At the time the birds ingest nectar they accumulate subcutaneous fat. Nectar does not reach the stomach but is held in the crop, which enlarges to accommodate it.