The endangered whio, or blue duck, is thriving in mountain waterways in Hawke's Bay, a survey has shown.
The Department of Conservation (DOC) census in January found 18 breeding pairs along 33km of waterway bordering the Forest Lifeforce Restoration (FLR) Trust's Maungataniwha Native Forest.
This year's survey also found 32 juveniles along the same stretch of water.
The result was not significantly different from the census three years previously, which found 19 breeding pairs along 41km of river, and 29 juveniles.
DOC biodiversity ranger Helen Jonas said the finding shows the outlook for the whio in this part of New Zealand remains encouraging.
The 2011 survey used a dog to sniff out ducks, which this year's did not, and a dog may have found more whio, Ms Jonas said.
The FLR Trust's work with whio at Maungataniwha is funded by Genesis Energy as part of the Whio Forever project - a five year $2.5 million dollar programme, managed by DOC, which will double the number of secure breeding sites around the country.
The Maungataniwha was classified under the project as a recovery site, which means it receives some form of pest control. Higher-priority breeding areas are classified as security sites.
The area has double the density of whio of other recovery sites, and similar results have been duplicated in informal counts elsewhere in the forest.
This indicates substantial populations are likely to exist across the southern Whirinaki and Te Urewera ranges, said Maungataniwha estate manager Pete Shaw.
"We're hoping these results indicate at least a partial plateau in the decline of whio across inland Hawke's Bay," he said.
"To get similar numbers from two surveys, conducted three years apart, is immensely encouraging."
The survey consisted of walking in or alongside rivers and streams, crisscrossing them and, in some cases rafting or tubing them, to look and listen for The Forest Lifeforce Restoration Trust was established in 2006 to provide direction and funding for the restoration of threatened species of fauna and flora in native forests within the Central North Island.