A team of river-rafting conservationists has discovered a thriving population of the endangered blue duck in back country.
Maungataniwha Native Forest estate manager Pete Shaw led the group of nine into the Hawkes Bay forest to look for the duck, which is also known as the whio and features on the $10 note.
The 6000ha forest, owned by businessman Simon Hall and part of a large area used by the Forest Lifeforce Restoration Trust to restore threatened fauna and flora, was known to be home to the blue duck, Shaw said.
But the group was stunned to discover 19 breeding pairs, 13 ducks and 29 juveniles along 41km of waterway.
There were thought to be about 2000 blue duck in New Zealand, which was "bugger all", he said.
"To go up the back country and see just one is so special ... given their numbers are declining we're pleasantly surprised to see that they seem to be doing so well up there."
Numbers now exceed the population density of many other North Island sites.
The high number of young ducks was also good news because nests were often targeted by stoats, Shaw said.
The group spent three days walking and rafting along streams, examining signs of the ducks, including their faeces.
"Conservation people spend a lot of time looking at poos and rubbing it between their fingers," Shaw said.
The area surveyed - the catchment areas of the Waiau and Te Hoe rivers - has now been classified a recovery site by the Whio Recovery Group.