The Wildlife Service followed that example in 1964 on Great South Cape Island, near Stewart Island. Rats had made it to the island, probably on muttonbirders' boats, and decimated the bird population. Two species were completely wiped out.
A rat eradication programme made the island pest-free again. New Zealand led the world in pest eradication.
Kevin says every decade, the land area that's been able to be made pest-free has increased 10-fold. In the 1990s it was Kapiti Island, 2000ha in all. In the 2000s it was Campbell Island, 11,300ha. New Zealand technology has eradicated rats from South Georgia Island in the southern Atlantic Ocean — 100,000ha.
Kevin says given the rate of increase of areas being made pest-free (rats, mice, weasels, stoats, ferrets and possums) it's feasible that by 2050 mainland New Zealand's 27 million hectares could be pest-free too.
"It's a big stretch, no question, but it's well within our reach. If you follow the maths you realise that every decade the largest area that we've been effective at eradicating rats has gone up by a factor of 10. If this carries on, and there's no reason why it shouldn't, then we should be doing 1 million hectares in the next decade somewhere in the world and then 10 million in the 2030s."
Kevin points to the example of the moon landing. In 1961, when JFK declared the USA had to send a man to the moon, the best the NASA had done was sent an astronaut into space for 15 minutes. Eight years later, it sent men to the moon and back. However, the rocket technology was fundamentally unchanged.
Kevin says the same thing generally applies to Predator Free. The fundamental tool — rat bait (brodifacoum) — has remained unchanged for nearly 60 years, but it's gone from hand-placed baits to helicopter delivery using buckets and GPS for precise placement.
"A lot of what we can do to go predator free is about perfecting it ... at this point in time we don't have to have a revolution in technology to make it work."
Kevin says what will be needed for successful mainland eradication will be ways of getting that very last pest, and that's the challenge scientists are working on, perhaps by using pheromones to attract them, or some other method that doesn't involve food.
The idea of making New Zealand totally predator free had been thrown around for years, but it wasn't until 2012 that Forest and Bird brought a range of experts and scientists together to discuss whether it was realistic.
When each rat, stoat or possum expert agreed that yes, given unlimited resources and public acceptance, that it would be possible, the idea of Predator Free New Zealand 2050 was born.
"At that point, we realised that we weren't wasting our time," Kevin says. "What was really neat about that was the moment the possum expert said yes as well, there was an 'oh my God moment' and we realised suddenly that this theoretical idea was possible."
That meant a shift from thinking about controlling pests, by simply trying to keep the numbers down, to completely eradicating them all together.
It's an idea that people across the country are embracing, with thousands of members of community groups already spending their weekends doing pest control in local forests or catching pests in traps in their backyards and urban areas and public conversations occurring about responsible cat ownership.
Kevin says while some people are opposed to using poison to control pests, New Zealand's environment is unique, and we have a responsibility to protect it.
"Clearly using things like toxins, we have to use them really carefully, ethically, humanely and minimise environmental damage at all times, but it we can eradicate these species, that's a New Zealand free of toxins, we'll never have to do it again, but while we are in the [pest] management scenario it's going to go on forever. So we have the ability to end this problem and surely that's a great place to get to."
Kevin says while the bulk of the money for Predator Free New Zealand 2050 will need to come from central government, there are massive economic benefits to the country to becoming pest free.
