Repanga/Cuvier Island
Image: DOC

Introduction

The Coromandel Islands are a vital safe haven for our nature. DOC ranger Rob Chappell talks about working on the islands, the impressive Mercury Island tusked wētā and the role the islands play in a Predator Free 2050.

Date:  20 January 2017

The Coromandel Islands provide sanctuaries for species which have become locally extinct on the mainland, and can be defended from the pressures of pests – including us humans. DOC ranger Rob Chappell is a pretty lucky man - his work has taken him to islands where most people can't go.

He has seen islands turn from pasture to thriving nature reserves and species teetering on extinction, brought back to flourish.

Repanga/Cuvier Island in 1970.
Repanga/Cuvier Island in 1970
Image: DOC

Repanga/Cuvier Island 2016.
Repanga/Cuvier Island today
Image: DOC

Rob recently led a small team to Repanga/Cuvier Island. While the team scoured the islands steep cliffs for destructive moth plant, Rob was busy setting tracking tunnels. On the mainland, this is typically done to detect the presence of pests like rats, stoats and hedgehogs.

He can remember a time working on Repanga/Cuvier Island when "we'd have competitions to see how many rats we could kill while we were cooking dinner. In the hut, at night you could take a torch and see them in the forest, and you'd be lying in bed and they'd be running over you".

With goats and cats removed from the island by 1964, the large population of rats left behind was finally eradicated in 1993.

Rat prints.
Lure is placed on an inked card and any creature taking the bait leaves behind telling prints. These prints belong to a rat.
Image: DOC

Gecko prints.
Without pests, native species return to their ecological niche and different tracks appear in the tunnels. These are from a native gecko.
Image: DOC

Rob was especially hoping to see one very unique set of tracks on this trip. The impressive Mercury Island tusked wētā (Motuweta isolata) came within a hairsbreadth of extinction.

The species was only re-discovered in 1970, and then only on the predator-free Middle Island.

Around 8000 years ago, the Mercury islands were connected to the mainland and these carnivorous "insect dinosaurs" would have roamed across the entire Coromandel Peninsula.

Despite the impressive combat gear of the males (who rub their serrated tusks to make noise), they are an easy meal for hungry rats. In the 1990s we discovered only 3 individuals could be located.

Mercury Island tusked weta.
This image shows the scale of the Mercury Island tusked wētā and size of their tusks
Image: DOC

Mercury Island tusked weta.
Mercury Island tusked wētā
Image: DOC

Weta prints.
Wētā prints
Image: DOC

Rob worked with Land Care Research on a successful captive breeding program and in 2000 the first tusked wētā were introduced back to a range of islands in the Mercury archipelago.

Despite a wild-to-wild translocation of tusked wētā to Cuvier Island in 2008 and 2011, only one track was seen at the last trip 18 months ago. When Rob returned to base from this year's monitoring, he was over the moon.

Of the 10 tracking cards placed, 4 showed tusked wētā tracks - and in good numbers. We now have potentially "thousands" of tusked weta successfully breeding on 7 Coromandel islands.

Predator Free 2050

Rob is passionate about the role the islands play in a Predator Free 2050.

Rob Chappell.
Rob Chappell checking a pyrcorft petrel chick on Cuvier Island
Image: DOC

"New Zealand must have been an amazing place pre-people, because it really had some incredible stuff that no other country in the world had, and bloody amazing at night time. We're lucky cos within the mercs and the aldermans we have five islands, that although they've been severely burnt, are relatively unmodified. They haven't had pests on them beyond humans, so they've functionally got the species on them that have probably been there forever. We can actually use them as a benchmark for what we're doing on islands like Ahuahu/Great Mercury Island and hopefully one day on the Coromandel Peninsula too".

In a Predator Free New Zealand, the seabirds that make the islands their home, would have made nesting areas in our inland forests.

"We've got a scientist looking for black petrels on Moehau at the moment, I've heard seabirds up there. We have a greater range of seabirds breeding in the Haurkai Gulf than any other place on the planet. The bonus is, now we're heading towards Predator Free New Zealand 2050 we're managing those populations to a point where when it may be that we can go to places like Moehau and the birds will come back automatically because the predators are gone. So that makes it pretty damn special."

"We have been fortunate and privileged to get to the islands at a time when, while the damage was reasonably intense, it's been recoverable and so the islands now are in a position where we can actually use those to create places like Tiritiri Matangi, and allow the public to go to Tiritiri Matangi and enjoy what New Zealand once was. But that has only occurred because we've had these incredibly special places - that we can defend, and it's all about defending those special places"

"It just takes people and time in the meantime. We've got this amazing ark we can maintain intact, hopefully forever. We've got great management support; we've got the skills and we just need the right resources and to ensure the next generation can carry on the good work"

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