"Our database includes several encounters from this area and other parts of the Heaphy Track, and, with sustained predator control in these areas, I'm reasonably optimistic that our South Island kokako could still be surviving there," Mr Nilsson said.
The trust had also received very credible reports from: the Milford Track (up the track from Sandfly Point), the Cobb Valley (Chaffee Hut), the Richmond Ranges (near mid Wairoa Hut), Doubtful River (Lewis Pass area) and most recently, Spur Track in Hanmer Forest Park.
However, a photograph remains as elusive as the bird itself.
"We still need definitive evidence - a photo or video - but we really feel that we are getting closer with the help of so many people who are out walking, tramping or hunting and know what to look and listen for. We are very optimistic that proof will be found soon."
- Greymouth Star