Conservation Dog Mart with two whio.
PHOTO: Lyn Hassell

A five-yearly whio (blue duck) census has confirmed the boom in the number of these endangered birds across Egmont National Park.

With ongoing yearly monitoring and the 2015 whio census conducted on eight monitored rivers within the national park, a lot is already known about the increase of whio numbers in these areas.

The 2020 whio census focused on whether these taonga are moving into previously uninhibited territories. As a result, 11 new rivers were surveyed by Department of Conservation (DOC) biodiversity rangers, their two conservation dogs and volunteers between January and March 2020.

The results are positive as whio are on the 11 newly surveyed rivers and seem to be thriving with evidence of breeding successes. This is a good sign of whio establishing new territories across the national park. During the 2020 census 15 pairs were located, with eight of those breeding; another 18 single whio were located, along with 17 juveniles. Two of those juveniles were released in March 2020 to provide new genetics to the current population.

The protection of these whio was helped by the reduced predation of whio eggs and ducklings due to the 2019 aerial 1080 predator control operation as well as most of the surveyed rivers already having comprehensive trapping networks in place.

DOC Biodiversity Ranger Joe Carson is pleased with the results.

“It’s awesome to see how well the whio are doing. Every river we surveyed had whio living there and several showed presence of fledged offspring. It is really exciting and has completely expanded our aspirations for ongoing growth of the whio population across Taranaki,” she says.

Whio are fiercely territorial and a pair need about a kilometre of fast-flowing river or stream for themselves. So, with around 200 whio now living around and across the national park, work is underway to maintain and increase trapping networks by another 8700 hectares.

“Our team and volunteers have worked really hard to rebait the stoat control network before winter and we will be increasing predator control around the southern and western side along rivers later this year,” says Taranaki Mounga Acting Project Manager Sera Gibson.

Whio are found nowhere else in the world and are rarer than some species of kiwi. The whio population in Taranaki has been growing with a 71 percent increase in ducklings located during the 2018/19 breeding season.