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Sap feeding behaviour of North Island kaka (Nestor meridionalis septentrionalis, Lorenz 1896) in plantation forests

North Island kaka (Nestor meridionalis septentrionalis) damage plantation pines (Pinus radiata and Pseudotsuga menziesii) in the Whirinaki Forest. Kaka strip pieces of bark off the trunks to gain access to the sap beneath. Three methods were used to investigate this behaviour. Firstly, the Whirinaki and Kaingaroa Plantation Forests were surveyed to investigate the current levels of damage and the physical characteristics and location of damaged trees. Secondly, the movements and habitat use of kaka were investigated by radiotracking. Finally, the diet of kaka was determined, through direct observation, and seasonal changes in diet and damage frequency were documented. The highest level of damage in a sampled compartment was 40% of surveyed trees (n= 100), but 78% of the damaged trees had only 1-2 damage patches. Why some trees were damaged but not others was not determined because there was no relationship between damage and diameter at breast height (DBH), or tree position relative to topographical features. Kaka damage occurred up to 1 km from the native forest. Trees suffering from crown dieback were no more likely to have damage than trees without dieback. At least 56% of trees suffering from crown dieback (n= 144) in the surveyed compartments were not damaged by kaka. The average core home range size for kaka, over 1 year, in dense podocarp forest was 15.5ha (n=6). All home ranges were within 2km (flying distance) of the exotic forest. Only one of these birds bark stripped in the exotic forest, where it spent up to 97% of its time during September and October. There was a large degree of overlap between home ranges, although there was less overlap in the specific use of this space. Monthly changes in activity centres occurred often over the course of the year, but birds typically returned to areas where they had been previously; the average change in the position of activity centres each month was 203m. One bird had a large expansion in its home range size in July when few food sources were available but it did not use the exotic forest. This coincided with a time when there was a low level of damage in the exotic forest. Four categories of food accounted for all of the feeding observations of kaka (n=2628): berries (24.3%), sap (24.0%), seeds (29.8%) and insects (22.0%). Eleven different tree species were used for food, and two of these were exotics; exotics accounted for 21.8% of total feeding observations and 38% of all sap feeding observations (n=366). Three podocarp species accounted for more than 50% of total feeding observations but only 6.7% of sap feeding observations. Seasonal changes in diet were evident. Berries were eaten from January-June; insects from March-October; seeds February-March and September-November; and sap from September-November. Bark stripping occurred mainly from September-December, with Douglas fir used during September and October, and tawa from October-December. This may be associated with an increase in sap sugar levels at the start of spring.
Type of thesis
Beaven, B. M. (1996). Sap feeding behaviour of North Island kaka (Nestor meridionalis septentrionalis, Lorenz 1896) in plantation forests (Thesis, Master of Science (MSc)). The University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/14227
The University of Waikato
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