Boxing Day Kaka Count by John Ogden

Environmental News Issue 13

The kaka (Nestor meridionalis) is a ‘nationally endangered’ native parrot, quite closely related to the kea of the alpine zone of the South Island. When Europeans first came to New Zealand kaka were very abundant, but by 1900 they had declined to localised flocks mostly in remote forested areas and on the larger off-shore islands. Numbers have continued to decline since then and the remaining populations have become more isolated (Robertson et al. 2007). The decline is largely due to predation by stoats and rats, and, in beech forest, competition with introduced wasps for honey dew. Great Barrier is certainly one of the few places in the country where they can be seen easily and one of their main predators is absent. Kaka are noisily conspicuous, and strong fliers, so it is easy to get the impression that there are more about than there really are. That was the reason for our ‘simultaneous’ kaka count on boxing day (26th Dec. 2007).

Over 50 people completed 45 ‘kaka count’ data sheets that evening. We had a pretty good coverage of the whole island (see Table), although, as expected some of the more remote places such as Hirakimata and Te Paparahi were not covered. However, a total of 222 birds were counted. If we include the three barbequed by Wesley Crankhandle and his mates at Okiwi that comes to 225!

As many correspondents pointed out, the day was very windy and birds generally were not much in evidence. Not everyone counted during the prescribed hour, and because of this, and also because some counts were on ‘adjacent’ properties and many counted birds were on the wing, we cannot be sure that some birds were not counted twice. We can get around this by assuming that the maximum single count for any ‘location’ gives us the minimum number present at that location (Wesley may have to think about that). On that basis we can say with some certainty that at least 141 different birds were counted. Taking into account the other data provided about the numbers seen in the previous week, or normally seen in the vicinity of the counter, provides a figure of 221.

Our count represents a sample rather than the whole population. However, the uncounted areas of the island, although large, may not contain many kaka at this time of year. I say this mainly because almost all the reports said the non-flying birds seen were feeding in pohutukawa, puriri, or pine trees, or in flax. As these plants are much commoner in the coastal areas than further inland it seems unlikely that there were a lot of birds somewhere else feeding on something else. I would ‘guestimate’ that the true adult breeding population is in the range of 200—300 birds.

Thanks to all permanent Barrierites and visitors who took the trouble to participate. We will send you a slightly more detailed synopsis in due course. Any further counts or comments will be welcome. Phone John Ogden at Awana on 4290980.

References:
Robertson, C. J. R., Hyvonen, P., Fraser, M. J. & Pickard, C. R. 2007. Atlas of Bird Distribution in New Zealand. 1999-2004. Ornithological Soc. of New Zealand Inc.