A $5000 reward offered to anyone who can confirm the South Island kokako is still alive, generated 40 reports of possible encounters, and interest from around the world.
The South Island Kokako Charitable Trust announced the reward last month.
The bird was considered extinct until 2013, when credible sightings prompted a reclassification.
Kokako trust spokeswoman Inger Perkins said the response had been phenomenal, and it had media interest from at least three European newspapers and news agencies.
"We have received over 40 reports of possible encounters, some recent and others from longer ago, stretching back a few decades for a few of them," Perkins said.
"Since the trust's website was set up a few years ago, a handful of possible encounters are logged each year, so to receive so many reports in the past month is a fantastic result."
Perkins said they were busy following them all up and were feeling "pretty positive" about several of them, which corroborated previous reports.
When the trust had analysed and compiled all the information, it would publish the most likely areas so that enthusiastic searchers could head out and find the evidence.
A Grey Valley expedition is already in the pipeline.
"We also think that some people may be keeping their encounters under their hats so that they can get that evidence before sharing. Whichever way brings us the evidence, we're happy and we're eagerly awaiting the opportunity to pay the reward."
Geoffrey Reid, a young environmentalist, said last month he heard the bird calling as recently as June 2016.
"I have been up and down the West Coast in and out the bush over the last couple of years and have heard birds in birds in multiple locations, some even calling to each other."
The Department of Conservation said that when South Island kokako were shifted from extinct to "data deficient" a couple of years ago, it was on the basis of a large number of possible sightings presented in a submission.
"Those sightings are likely to have been all that were known about at the time, but they had been collected over many years, and there were less than 100," DOC spokeswoman Jose Watson said.
"None of the sightings were supported by evidence such as photos, audio recordings, or feathers."
The sightings DOC knew about had been in a variety of locations.
The trust would prefer a verifiable photograph or other physical evidence of the bird over claims to have heard its calls.
Further information about the search and the reward is available on the trust website www.southislandkokako.org.
- Greymouth Star