On a cloudless Wellington afternoon, Nick and I ventured off into the bush to check out the self-resetting traps made by Goodnature. Our guide was Robbie, one of the three lads involved in this local Wellington firm from the outset. As we trudged up the steep hills of the Orongorongos we took regular breaks so Nick could gasp for air, and we could hear about how the company got started.

The three of them were design students, and upon graduating were all busily carving out a career for themselves in their craft. Robbie was doing some work for DOC, helping them develop the DOC 200 trap which at the time was cutting edge technology in the craft of killing stuff. An off the cuff remark by a DOC staff member ‘now all we need is a trap that resets itself’ got Robbie thinking. A brainstorm with his mates yielded over a hundred different ideas on how to kill a rat, but things really came together when they had the idea of using a gas canister to power the trap. With the help of a DOC innovation grant they shelved their ‘traditional’ design work got started on Goodnature.

Halfway along the gully checking the trap lines and we could already see why a self-resetting trap makes sense. To control predators across the massive New Zealand landscape you need to create a trap line every 100 metres, with traps 50 metres apart all down the line. With most traps, you need to check them monthly in case something has been caught. This is no easy task; this particular trap line we were walking along was typically thick New Zealand bush, complete with vines, fallen trees and the occasional sheer drop. Nick fell over a total of five times, me once, and at one point Robbie offered to call in the rescue helicopter.

With their resetting trap, Goodnature had invented something that needed to be checked once a year rather than once a month. This meant volunteers and DOC workers had 11 fewer trips to check trap lines along the sort of terrain that we were in. The Goodnature lads were never satisfied, and were always innovating to make their creation last even longer. Of course Nick would have preferred if they could have eliminated the trip altogether. Hearing a thump we turned around to see only the curly hair on top of Nick’s head – he had slipped down a bank and impaled himself on a ponga.

Each of these trips to check traps takes time and effort – Nick was already grunting something about needing a massage. So it is worth it for DOC or volunteer groups to spend a bit more money on the trap up front if it saves them 11 trips (and presumably 11 massages) a year later on. Despite Goodnature traps being more expensive, they pay for themselves in 17 months because of the reduced checks needed. With over 200,000 traps out there in the wild, you can see that Goodnature could potentially change the trapping landscape in New Zealand forever. If we spend less time checking each trap, we could potentially put a lot more traps in the wild, and kill a lot more stuff.

And these traps had certainly been killing. Robbie talked about how usually the traps will kill a lot of animals in the first few nights, and then numbers drop off as local populations dwindle. Slowly the juveniles and mice come out because the large rats are gone, and pretty soon the traps are just stopping re-invasion from outside. This particular trapping area we were walking through was 47 hectares, and had 76 traps within it. They had killed 35 rats in the first night, and 2-3 each night afterwards. Within two weeks Robbie felt the rat population had been knocked down to negligible levels. Around some of the more popular traps was a little pile of rotting rat bodies. You would think that the sight of their dead colleagues would scare off rats but it only seems to attract them – after all a dead rat means there is some new territory to take over.

So if the traps are working, when will we see them taking over the DOC trapping network? Not anytime soon, as they have to pass some rigorous field tests first. DOC is conducting trials, but they won’t be done until 2015. In the meantime Goodnature is making their money selling their technology overseas. Everyone around the world wants to kill rats, and their technology has also been applied to such diverse animals as feral cats in Hawaii and mink in Sweden. Traps face far lower regulatory barriers than anything involving poison, so this is technology that is more exportable.

After an hour and a half of walking Nick had started wheezing, and Robbie took this as a signal that we should head back to the car. We turned down the hill, and followed the line of traps down a ridge. In a patch of kamahi trees (a favourite of possums) we found a massive possum, freshly killed by their possum trap (the A12). Robbie took the opportunity to show us how the traps worked from a humane killing perspective. Possums have a pretty small brain and it is covered with thick muscle to hold their heads up. The trick of making these traps is getting their head in exactly the right place so that the bolt goes through their brain and kills them instantly. Sure enough as Robbie pulled back the fur of the possum there was the bolt hole – right in the centre of the head.

Now that the traps are working well, with failure rates down to about 2%, more of their effort is going into improving pastes. After all, the further away you can attract predators from, the fewer traps you need. We know that possums for instance only spend 10% of their time eating; our forests have so much tucker that they can spend 90% of their time mating and fighting. As a result they are capable of travelling several kilometres in a night, and will travel to a trap if the paste is attractive enough. Also, the longer the pastes last the fewer times it needs to be visited for pastes to be changed. They are currently working on a synthetic paste that mimics a rat’s scent – we called it Eau du Rat. Nick and I had a whiff – we can assure you it won’t be on the shelves anytime soon, it smelt a bit like a mouse cage in a pet store.

Finally we broke out of the bush and into the daylight. As we got to the truck Nick dropped to the tarmac to kiss it, and vowed to never leave civilization again. On the trip back Nick discovered that his camera had been busted during one of his falls, which was confirmed by the camera sized bruise on his chest. Robbie dropped us back into town and went off back to their Kilbirnie office and factory which is churning out around 300-400 Goodnature traps every week. Let’s hope that number continues to grow, because it means we will be that much closer to a Predator Free New Zealand. The sooner the better because Nick pointed out while taking one of his frequent impromptu sit downs, the forest we were walking through was almost bereft of bird calls.

At $170 a pop, Goodnature Traps are more expensive than a single setting trap. But if you have a real rat or possum problem, and want to avoid the use of toxins then they might well be worth the investment. They are particularly useful in places where traps are difficult to check – maybe you have a chunk of bush or a maybe a bach you don’t visit often. Or maybe you just don’t like dealing with dead predators and prefer to leave them in a little pile under the trap!