Feeding energetics of kaka in South Island beech forest
Radio-equipped kaka (Nestor meridionalis meridionalis) studied in Big Bush State Forest spent 35% of their feeding time digging out Ochrocydus huttoni larvae. The larvae had a high energy value (34 kJ/g), and 91% of this energy was assimilated. However, the cost of digging out one O. huttoni meant that kaka made a net loss of energy. In the beech forests in our study area, honeydew is the only high-energy food eaten by kaka that is produced throughout the year. Kaka gleaned 175 droplets per minute, and assuming 100% assimilation efficiency, made a large net gain of energy when feeding on honeydew.
If kaka in our study area rely almost entirely on honeydew to balance their energy budget, and O. huttoni for most of their other nutrients, then anything affecting either of these resources may have serious implications for the long-term survival of kaka in this habitat.