The call of the grey ghost

The South Island (top) and North Island kōkako, painted by John Gerrard Keulemans (click for image credit)

The South Island (top) and North Island kōkako, painted by John Gerrard Keulemans (click for image credit)

Those who are lucky – and persistent – might catch a glimpse of it gliding into the bush, or a snippet of haunting song. Nicknamed ‘the grey ghost’, it is the elusive South Island kōkako.

Extinct?

For 40 years it had been seen only occasionally – and none of those sightings had been officially verified. In 2007, to the dismay of some conservationists and ornithologists, the South Island kōkako was declared extinct by New Zealand’s Bird Threat Ranking Panel.

Those who were convinced the bird still existed began a campaign to prove it. They felt there was a moral obligation to do so, as the bird was certainly endangered, and without official acceptance it existed, there would be no support or funding for saving it.

A database was set up for recent encounters with the bird. Reports have come in from scattered locations all around the South Island, but mostly towards its western side. They are often from trampers, hunters or trappers.

In 2012 researchers chose 13 of the most compelling reports from their database of 241, and submitted them to New Zealand’s Bird Threat Ranking Panel. This was enough for the panel to change the South Island kōkako’s status from ‘extinct’ to ‘data deficient’.

Following on from that, the Ornithological Society of New Zealand’s Records Appraisal Committee deemed one of those reports ‘accepted’, and considered several others ‘probable’. These successes were announced in the media at the end of November 2013.

The hunt for evidence

Work has just begun, and for campaigners the race is on to get the hard evidence they need to prove the South Island kōkako exists for sure. Last summer holidaymakers walking the Heaphy Track snapped hasty photos of what they were pretty sure was a South Island kōkako in the trees above. The images are blurry, and show only a grey, kōkako-shaped blob high in the branches, but they give hope that clearer photographic or video evidence may emerge soon.

Threats

The greatest immediate threats to the South Island kōkako (as to many native birds) will be introduced predators – particularly stoats, rats, possums and feral cats.

2014 is going to be a mast year in New Zealand – when beech trees and tussocks produce especially large volumes of seed, beginning an ecological chain reaction that results in predator populations exploding. The South Island, rich in beech forest, will be especially hard hit.

Why so elusive?

If the bird has survived, it has presumably done so in small numbers for a century or more.

The South Island kōkako is much shyer than its North Island relative, and it doesn’t seem to be curious about intruders in the same way many birds are. It’s difficult to draw it into the presence of humans. Perhaps it was always this way, or perhaps only shyer birds survived after the arrival of humans and introduced predators – shyness may well be a heritable trait in these birds.

Recognising a South Island kōkako

Sightings are ranked. Those that are considered most compelling involve seeing a bird that fits the description not more 10 metres away with the naked eye, or the equivalent through binoculars.

Kōkako are smaller than kererū (wood pigeons) but larger than tūī. Crucial to identification is seeing the wattles on either side of the throat. On the South Island kōkako these seem to range from bright orange to pale yellow, and they sometimes have a bit of blue on them as well. The wattles are probably most prominent around breeding season – these birds nest from December to March.

Less compelling, but still important, sightings may involve seeing the bird at a greater distance away, or not getting a clear view of the wattles but seeing the bird exhibit defining kōkako-like behaviour: either running along branches or logs, or making large hops or leaps.

A shy song

‘Non-visual’ reports involve hearing the bird’s song. This resembles that of the North Island kōkako, but, like everything else about the grey ghost, is more elusive. The South Island bird doesn’t repeat the same notes over and over. It’s more likely to call once, then stop. There are also historical reports of it mimicking other birds, and in its repertoire it has harsh, animal-like sounds – some like goat and deer.

One classic kōkako call sounds a little like blowing over the neck of an empty glass bottle. Researcher Ron Nilsson also told me, ‘The kōkako are the only birds in New Zealand who have the ability to slide a note from one octave to another. If you are lucky enough to hear one of these notes then there is only one bird it can possibly be, and that is a kōkako.’

If you think you’ve encountered a South Island kōkako, report it at the Grey ghost website and at New Zealand Birds Online.

Thanks for assistance to Ron Nilsson and Alec Milne.

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