Rare whio (Blue Duck) are returning to the streams of inland Hawke’s Bay following devastating snowstorms in August 2016 and subsequent flooding. An annual survey of streams in the Maungataniwha Native Forest conducted in November last year by the Department of Conservation and the Forest Lifeforce Restoration Trust shows that whio numbers have recovered to pre-storm levels and that the birds are slowly re-populating most sections of waterways they had to abandon.
The catchments of the Waiau and Te Hoe rivers in the Maungataniwha Block stewarded by the Trust had been designated a National Recovery Site for the endangered duck. The area is one of the largest and most southern habitats of the wider Te Urewera whio population. But the storms and floods of five-and-a-half years ago reduced the population from 19 breeding pairs to just four.
Pete Shaw, the Trust’s forest manager, said last year’s survey showed that whio populations on all waterways had recovered or even improved slightly except for a small section of the Waiau river.
“We suspect that ongoing and highly effective predator control at Ngatapa and Pohokura stations, along with trapping at Maungataniwha funded by the Trust, has a lot to do with this recovery,” he said. “As has the success of the joint DOC and Ngati Whare recovery work in the Whirinaki Te Pua O Tane Forest.”
Whio are an indicator species which can be easily monitored to provide an insight to forest health and completeness (ngahere mauri). The annual whio surveys help determine what is happening within the region, not only for whio but for the whole range of forest birds that are also susceptible to predation, climate change and weather events.
The survey is always conducted during the breeding season, when most breeding pairs would have nearly-fledged juveniles, to provide insights into breeding success. It involves walking, rafting and tubing the streams, looking and listening for whio and for sign such as faeces and calls. Features such as good-looking roost areas with protective overhead cover are given extra attention in case of any sign.
Search teams operate in the first and last hours of daylight as this is when whio are feeding and at their most active. A specially-trained whio detecting dog is used when available.