Hawke’s Bay come-back for rare Blue Duck
Trust property listed as a Whio recovery site
New Zealand’s endangered Whio, or Blue Duck (Hymenolaimus malacorhynchos), is thriving in the mountainous rivers and streams of inland Hawke’s Bay according to a survey conducted by the privately funded Forest Lifeforce Restoration (FLR) Trust and the Department of Conservation (DOC). The catchment areas of the Waiau and Te Hoe rivers, bordering the Trust’s 6,120 hectare Maungataniwha Native Forest, have now been classified a ‘Recovery Site’ by DOC’s Whio Recovery Group (WRG).
Similar Whio densities at the FLR Trust’s nearby Pohokura property, and duplicated in informal counts elsewhere at Maungataniwha, indicate that relatively substantial populations are likely to exist across the southern Whirinaki and Te Urewera ranges according to Pete Shaw, FLR trustee and Maungataniwha Native Forest estate manager.
“We’re hoping these results indicate at least a partial plateau in the decline of Whio across inland Hawke’s Bay,” Shaw said.
The census, conducted at the end of last year and the beginning of this, found 19 breeding pairs along 41km of waterway, a density described by the Trust as “immensely encouraging”. It also found 13 single ducks and 29 juveniles along the same stretches of water.
A post-survey report issued by the Trust and DOC says Whio numbers in the Maungataniwha block now exceed the population density of many other North Island sites. South Island sites are naturally less dense so are not included in comparisons.
The WRG classifies North Island sites it monitors as either Security Sites or Recovery Sites. The former are priority areas for DOC and there are four across the North Island.
Recovery Sites receive lesser amounts of funding but often have some form of stoat control. As with the Trust’s activities at Maungataniwha, stoat control at several Recovery Sites is funded and operated by private land owners.
At 0.47 pairs per kilometre the Maungataniwha Whio population density is approximately half the average of North Island Security Sites, but more than double the average density of Recovery Sites.
Maungataniwha’s close proximity to the Whirinaki Security Site, little more than 15km away in a straight line, underscores its appeal as a recovery site according to DOC biodiversity ranger Helen Jonas.
“Juveniles will easily be able to disperse between these two sites which will assist the WRG’s long-term goal of establishing ‘stepping stones’ between Security Sites,” she said.
The FLR Trust/DOC survey was timed for the Whio breeding season in December/January, when most breeding pairs would have juveniles.
“It was important that we got some idea of juvenile production,” Shaw said.
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 sign such as faeces and calls. Features such as likely roost areas with protective overhead cover were examined particularly closely. Whio Recovery Group Leader Andy Glaser also used a dog to sniff out concealed ducks.
DOC says the area’s Whio are benefitting from the extensive predator trapping undertaken by the FLR Trust in support of its Maungataniwha Kiwi Project, one of the most prolific and successful kiwi conservation initiatives in the country.
The Maungataniwha area has been included in the Department of Conservation Natural Heritage Management System (NHMS) as an ecosystem that is a good representative of its type nationally. NHMS attempts to identify and protect good examples of all of New Zealand’s ecosystems and it is significant that Maungataniwha is listed among them.
Whio themselves are the ninth highest ranked species nationally in the NHMS system, making them a priority for conservation efforts - particularly where a good population overlaps with a NHMS-ranked ecosystem.
The FLR Trust’s Maungataniwha Whio research project complements its Whio secure breeding project on its nearby property at Pohokura. In addition to these initiatives and the Maungataniwha Kiwi Project it runs a series of native flora and fauna regeneration projects. These include a drive to increase the wild-grown population of Kakabeak (Clianthus maximus), an extremely rare type of shrub, and the re-establishment of native plants and forest on 4,000 hectares currently, or until recently, under pine.