Beyond Barrier Conservation dogs and the war on rats (aka the adventures of Milly)

by Scott Sambell

Journeys to our very special offshore islands

In his multi-part series, Scott Sambell recounts his recent journeys with Milly to some of our very special offshore islands, and we see a glimpse of what a past (and future?) New Zealand may have been like...

PART 1:

Rangatira Island (South East Island)

Prologue

Islands are always going to have unique and fantastic wildlife due to the fact that – by definition – you can’t just walk over to them and set up a life for yourself.  The islands that sit on the continental crust of Zealandia are particularly unusual in that when they broke away from Gondwana 85 million years ago they neglected to take with them any mammals (apart from a few bats). When the first humans arrived they were stunned by what they found.

Whenever I come across a globe of the world, I instinctively spin it around, tilt it over a bit, and look for New Zealand. I find it easiest to first locate the distinctively huge land mass of Australia and then trace an arc down to the southeast until I hit that familiar, yet almost indiscernible archipelago of home. Now, if you were to repeat that exercise on a much larger globe and trace an arc from the now familiar land mass of New Zealand down to the south east again, you would hit another indiscernible archipelago called the Chatham Islands. Here you have a tiny island off a tiny island and the wildlife gets another factor of distinctiveness.

Now, trace an arc down to the south east of the main island and you come to yet another, even more isolated island. Pitt is an island off the south east of an island, off the south east of an island. But we’re not quite finished yet. Keep your finger on Pitt Island and trace an arc one more time down to the south east. Here, with a factor of isolation that hurts to even attempt to calculate, is our island, off-an-island, off-an-island, off-an-island - and it’s called Rangatira.

Which is where our story begins..

Journey to the actual end of the Earth

Milly the rat dog cowered in her box.  Although she is the equal smallest of all the DOC fully certified conservation dogs, Milly is by no means the least brave. Even the mighty Labradors and springer spaniels that tower above her would have been cowering in these seas. I sat steadfast on her box with my legs wedged between a crate of solar panel equipment and a plastic tub containing about two cubic metres of despondent looking crayfish. It wasn’t the most comfortable of positions for either the dog, the handler or the crayfish but these ‘crayboats’, being the Chatham Island equivalent of a water taxi, are the only possible way to get out to this island.

To the great relief of the dog and handler, the massive twin turbo diesel engines dropped in pitch and immediately there was a lot of action from those on board. I took this as a cue to stand up and try to look helpful and Milly took it as a cue to whimper slightly, but in a professional, conservation-dog kind of way.

Suddenly there were buckets, boxes, machinery, solar panels and (to my genuine surprise) an actual full-size fridge being heaved up to the for’ard deck for unloading. 

The only permanent residents of Rangatira are a community of some of the most rare and threatened ‘non-mammals’ in the world so there hasn’t been the demand as yet for the construction of a wharf. The modus operandi for disembarking in these swells is to get onto the bow with whatever freight you can comfortably lift and, within jumping distance of the rock shelf, take a very large and confident step forward.

Fortunately, Milly the rat dog, having spent most of her four years on Aotea/Great Barrier Island, was very familiar with what was expected. The bow of the cray-boat dropped a metre below the rock shelf and then surged forward and up as the next Southern Ocean roller, pitched it forward. At that precisely practiced moment she took flight, traced a perfect parabola through the air, and came to land perfectly on all fours onto the rock shelf, closely followed on the next wave by her very relieved handler.

The only permanent residents of Rangatira are a community of some of the most rare and threatened ‘non-mammals’ in the world...

After four days of travelling by plane, car, light utility vehicle and boat, they had finally touched down on their destination and, after briefly stepping aside to avoid being crushed by a passing fridge, they surveyed the site of their latest mission.

The dog and his man

Milly and I have the coolest job in the world.  In short – we travel to places that don’t have rats to make sure they still don’t have rats. 

Anywhere else in New Zealand where you don’t have rats, you have a lot of native species. This is such a basic tenant of everything we do that our first task was to walk across the rock shelf and take a quick look around for shore plovers.  If the shore plovers are still alive, then that’s the first good sign you haven’t had a rat incursion since the last time you visited.  Only 175 shore plovers are left in the world.

As I climbed over the rocks that separated our landing site from the rest of the island, I encountered Milly doing her familiar uncomfortable pose which I now know to represent: “I just saw a bird, but I didn’t mean to see a bird, I promise I didn’t look at it on purpose, oh dear, I wasn’t looking really, I think I might just lay down here until it goes away” and I caught site of the 15 tiny tennis-ball-sized birds that she was cowering away from, in the rock pools below. We had just ticked the first box on our biosecurity checklist. 

Apart from being brainwashed since she was eight weeks old to ‘pretend she can’t see birds’, Milly has also been very thoroughly and methodically trained to serve as my ‘sense of smell’ in the forest.  When we first arrive at an island such as this one, we take stock of our surroundings, consider how much time we have, what are the most sensitive areas, what places would be most likely to give us evidence of an incursion, and then we head on out into the bush and give it a good sniff.  Usually.

An island owned by seabirds

Rangatira is a little different from many other islands I had been to. When rats were eradicated in 1963, many native species, as expected, began to thrive.  At latitude 44 degrees south and directly in their migratory path, the ones that stepped up on this island were the Procellariiformes - seabirds. 

I wasn’t quite prepared to step off the boat and into an ecosystem – an entire world – so completely owned by seabirds. Everything – absolutely everything about the island of

Rangatira has been shaped by seabirds.

The trees, plants and ground cover had been sculpted by the movement of a million seabirds, but the most striking feature was that the very island itself – the ground beneath our feet - was nothing but an enormous labyrinth of catacombs, excavated by the subterranean movements of a million burrowing seabirds. There is no solid ground on Rangatira.  If you were to take a step you would fall through three stories of the nearest seabird’s home.

...the ground beneath our feet - was nothing but an enormous labyrinth of catacombs, excavated by ... a million burrowing seabirds.

Now kiwis (the people) are nothing if not ingenious folk, so a system has been created so visiting scientists and confused dog handlers can move with relative ease across the island. In true ‘number 8 wire’ fashion, these ‘petrel boards’ as they are known, are a snowboard binding bolted to a two-by-one-foot section of plywood which increases your footprint. The alternative would be clumsily crushing the fragile home of either a Chatham petrel, fairy prion or two very cute species of storm petrel.

It turns out that a 5 kg miniature fox terrier Jack Russell cross falls just under the weight-to-footprint ratio required to punch through a seabird burrow, so Milly avoided having to don her own peculiar footwear. And so began our four days of trekking through the forest of an alternative universe where seabirds rule the planet, with a miniature snowboard strapped to each foot, being led by the nose of a brainwashed, bird adverse, Jack Russell terrier.

Pest free

Four days later, sitting on the back deck of the hut and taking the petrel boards off for the last time, I give a sigh of relief and my partner a quick rub for a job well done.  No rats.  In all honesty, there never usually is on these jobs, but at least we can say we have had a very thorough search.

What was once a land of cattle and men, now the domain of the seabirds. The cattle now extinct for over 50 years…50 years?  Hold on. This gave me a thought - Rangatira went from being trodden over by cattle, to being honeycombed by seabirds over slightly more than my lifetime. As this implausible concept began to sink in, I extrapolated to other places that Milly and I had checked in the last four years and began to think about what these pest free islands would be like after 50 years of the birds being free to do their own thing. Which leads to the question, what would a predator free New Zealand look like in 2100?

My daydream was interrupted by a black robin landing nearby, which reminded me we had another island to go to where these enigmatic little birds now rule the forest after coming as close to extinction as anything has ever been in the history of life on Earth.  But that story is for another day.  For the time being we had a boat to catch. I shouldered my pack and we made our way down to the crayboat that would take us to Mangere Island – the site of the greatest conservation rescue story ever told.

Which we will attempt to retell…in the next instalment.

Environmental News Issue 38 Spring/Summer 2017