Rat infestation not confined to Titirangi as populations double across New Zealand

Fearful Titirangi residents have been plagued by rats the size of small dogs but the plague isn't confined to West Auckland - pest controllers are reporting rat populations have doubled this year in all major cities across the country.

If you step outside the city, the problem gets a whole lot worse.

Out in the bush, pest controllers are catching twice as many rats, trapping 160 in one hit.

In the South Island, Pelorus Sound trappers have recorded six times as many rats plaguing their patch. 

Blame the "mega mast" - that's when weather conditions cause trees to produce tonnes of extra fruit. This mast is the worst in 45 years.

Usually, that'd be great news for the birds but after they've filled their beaks, all those leftovers attract their arch enemy - and we all know what happens when you cross a cunning rat with a docile native bird.

Nelson conservationist Debs Martin told The Project the infestation is the worst it's ever been.

"We've got double the most rats we've ever had where we've been doing our trapping project for almost ten years now," she said on Tuesday.

And it could have disastrous consequences.

"Where we are, we're trying to protect long-tailed bats. Now they're nationally critical. That's as endangered as you can get before you go extinct," she said.

Martin says the best way to trap a rat is to use peanut butter.

"Pic's peanut butter from Nelson. You can't go past it." she said.

Watch the full interview above.