Tui appear to be thriving after a joint Environment Waikato and community-funded pest control operation in the Maungakawa Reserve near Cambridge last year.
The operation – part of the Hamilton Halo project – spent $15,000 in October targeting possums and rats ahead of the tui breeding season over summer.
EW biodiversity officer Ben Paris said recent monitoring in the treated area detected no rats.
"This is an excellent result bringing clear benefits for tui breeding," said Mr Paris.
Maungakawa Rd resident Vanessa Moore – part of the Friends of Sanatorium Hill group which helped fund last year’s operation from WCEET community funding – said the number of tui visiting her garden had increased since the pest control work, an indication it was helping adult birds thrive as well.
"A dozen or so tui have been feeding regularly in our garden since early December," she said.
"I have not ever seen, for the past 13 years, three or more tui feeding together on one flax bush. But that’s happening now."
Mr Paris said that, under the Halo project, the Maungakawa Reserve will keep being treated ahead of the breeding season for the next two years.
"Our work at this and other Halo sites around Hamilton is aimed at increasing the number of these iconic birds around our city. We will continue to monitor results closely to ensure we’re getting value for money from our work."