From the $100 bill to a Canterbury valley: Missing mohua return after 20-year absence

Monday, 28 February 2022

One of the mohua checks out its new home.

Lucky trampers passing through one Canterbury valley might now hear the chatter and buzz of a bright-hued native forest bird, missing from the area for two decades.

Department of Conservation (DOC) staff released 41 mohua – or yellowheads – to the Poulter Valley in Arthur’s Pass National Park on Monday.

The sparrow-sized birds were flown from Chalky Island in Fiordland to join other small populations in nearby Canterbury valleys.

Mohua were once one of the most abundant birds in the South Island’s beech forests, but now there are thought to be as few as 5000 left, many on predator-free islands.

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However, mohua have mostly disappeared from their traditional homes. The birds nest in tree holes, making them easy prey for rats and stoats.

The birds were transported from Chalky Island in Fiordland to Canterbury's Poulter Valley.

In the latest bird threat level review, mohua were moved from ‘at risk – recovering’ to ‘at risk – declining’.

DOC biodiversity threats adviser Marion Rhodes said the goal was to return mohua to all the Canterbury valleys where they once thrived.

“Intensive predator control to protect the critically endangered kākāriki karaka [orange-fronted parakeet] that live in these valleys has also created favourable conditions for mohua.

A total of 41 mohua have been released in the valley.

“We’ve seen mohua numbers in the Hurunui South Branch increase to well over 100 birds, and the smaller Hawdon Valley population is also showing promise.”

Rhodes hoped the new arrivals would settle in the Poulter Valley, eventually dispersing to join up with populations in other valleys.

Te Ngāi Tūāhuriri Rūnanga liaison Arapata Reuben said after many years of predator removal work, the hapū was blessed to have the taonga species return to Poulter Valley.

It’s hoped the mohua spread to meet up with populations in other Canterbury valleys.

“We hope mohua will thrive in their kāinga (home) and that their waiata (song) fills the ngahere (forest) once again.

“One day when their population has grown, and it is sustainable to do so, our weavers will once again be able to use their feathers for weaving, just like their tīpuna did so many generations ago.”

Te Ngāi Tūāhuriri Rūnanga are mana whenua and kaitiaki of Poulter Valley, and Arthur’s Pass National Park.

Mohua Charitable Trust founder and chairman Nigel Babbage said it was a great day for the species, which is featured on the New Zealand $100 banknote.

“Back in 2007 there were only eight known mohua in Canterbury and now, due to previous translocations, the population numbers in the hundreds.

“We are stoked that this release will further enhance the mohua population and the genetic diversity of birds within it.”

Arthur’s Pass and surrounding areas previously hosted large numbers of mohua, but they were mostly gone by the 1980s.

Birds that hung on in the Hawdon and Hurunui north and south branches were all but wiped out by a surge of predators after a double beech mast – the dropping of huge numbers of seeds – in 1999 and 2000.

Mohua were successfully reintroduced into the Hurunui South Branch in Lake Sumner Forest Park, with two releases in 2008 and 2009. They were also returned to the Hawdon Valley in 2014, with a second release in 2017.

Rats, stoats, and possums are now kept to a minimum through extensive trapping and then use of aerial 1080 when their numbers increase too high.