Brian Rudman: Taonga or not, when it comes to rats, just kill them all

The 10-year battle some local Maori leaders have fought to stop the eradication of the kiore - the Polynesian rat - from Little Barrier Island is one of the oddest tussles of our time. It is a rat, after all. And I'm of the school that believes the only good rat is a dead one.

I remember travelling across some desert in India once, as you do, to visit a sumptuous marble temple topped with gold and silver domes, and alive with podgy brown rats.

You couldn't put your foot on the ground without the risk of squashing one. Devotees, who fed them milk and sweets, treasured them as the carriers of the souls of long-dead holy men.

As you may have gathered, I was not converted.

Whatever they were, they obviously knew they were on to a good thing. Indeed, given their obesity I doubt many would have been able to stagger out the door into the surrounding countryside even if they'd wanted to.

Closer to home on Little Barrier it's a different story. Taonga - or treasure - as their rats might be to the local tangata whenua, there are no temples, or food stations, erected in their honour. Unlike their Indian cousins, the kiore are left to scavenge - as it has been ever since their ancestors arrived hundreds of years ago - in the local bush.

According to conservationists, the results have been calamitous. Indeed, Forest and Bird calls the kiore's arrival in New Zealand a thousand years ago "one of the great biological holocaust stories of the past 10,000 years".

However over-the-top that metaphor, there's little doubt that the kiore, which came as on-the-hoof fast food with the first Maori migrants, created havoc with the existing natural order. The whole small end of the food chain - including a wide-range of insects, frogs, lizards, birds and bats - was pushed to, and in many cases over, the brink of extinction.

Forest and Bird say the before and after can still be seen in places such as the offshore Poor Knights Group where rodent-free Aorangi Island at night "is alive with animals that crawl, walk, run, slither [and] creep" whereas on a neighbouring island where the only introduced predator is kiore and "at night the whole place appears quite dead".

The Department of Conservation's long-term plan is to eliminate kiore and other rats from the offshore islands under its administration, to give the indigenous plants and animals a chance to regenerate and survive.

Tuatara, which were rediscovered on the island about 10 years ago, are the celebrity at-risk species on Little Barrier, but other threatened species include smaller lizards, Cook's petrel and the giant weta. Several plant species should also benefit.

That Kiore eradication works is not in doubt. You only have to look at the successful 1993 aerial drop of rat bait on Tiritiri Matangi, the open sanctuary Hauraki Gulf island, for evidence of that. There, the resultant profusion of seedlings and lizards was proof enough.

The poison drop on Tiritiri was preceded by the same protests as are being heard now. There were the worries of a small group of conservationists, fearing collateral damage among birds and tuatara and other animal life, and concerns from some Maori about their taonga being eliminated.

First, the collateral damage: There is evidence from here and overseas that predators can on occasion be killed by eating the carcasses of poisoned rodents. But it's not a perfect world. I prefer Victoria University professor Charles Daugherty's approach. He was one of the scientists who rediscovered tuatara on Little Barrier and is passionate about their long-term survival.

He says that "no one likes poisons but the choice is you lose a few tuatara by poisoning and then the population recovers or you just go on feeding them to the rats".

Then there's the kiore having some semi-sacred status which warrants their preservation because they came with the first Maori.

I find this very difficult to take seriously. The received wisdom is that the ancestors, when they came out of Asia, brought with them, among other staples, a caged supply of the local rat.

Over the ensuing centuries, as they gradually spread throughout the Pacific, the pre-Maori carried their meat supplies with them. A bit like the Europeans, who many years later arrived with pigs and cows.

Some Maori - though not all - now want a sort of kiore whenua status for their original livestock, similar to the tangata whenua status they have achieved for themselves as the first people of the land. This despite the destruction to the original fauna and flora the first four-legged migrant mammal has caused - to say nothing of his two-legged companions.

Truth is that both the first wave of human migrants and the second brought widespread destruction of the environment.

These days the kiore is just as much a pest and enemy of the indigenous flora and fauna as are the later arrivals, the ship rat and the Norway rat. Declaring war on two of the species while putting the other on some sort of pedestal makes no sense at all. I say kill them all.

Further reading:
nzherald.co.nz/environment