Huge "cat-sized" rats brazenly scurrying about in Titirangi have terrified locals, but this West Auckland village is part of a New Zealand that is being plagued by a rat infestation.

Pest controllers have reported that the population of this rodent has doubled this year in all major cities across the country, according to The Project.

Speaking to the Herald, Forest & Bird spokeswoman Megan Hubscher said that they are seeing a huge explosion in rat numbers in both forests and urban areas.

Rats as long as 30cm have been seen scurrying around Titirangi. Photo / File
Rats as long as 30cm have been seen scurrying around Titirangi. Photo / File

"2019 is what we are calling a mega mast year which means our native trees are fruiting really heavily and normally that would have fed our bird population, but these days it's feeding rats instead," she explained.

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"We are seeing some really alarming numbers coming through from our trapping groups around the country.

"For example, in the bat reserves in Pelorus Bridge near Nelson, normally they would be catching rats in 3 per cent of their traps, they are now catching up to 60 per cent."

"That's really bad news for the native bats they are trying to protect down there, and all the other wildlife that live in our forests as well."

A Waitakere kokako (called Francis) that's had its tail gnawed off by rats. Photo / Forest & Bird
A Waitakere kokako (called Francis) that's had its tail gnawed off by rats. Photo / Forest & Bird

Hubscher said that a lot of community trapping groups operating in urban areas around the country are seeing the same explosion of numbers in our cities as well.

"Trees have been fruiting very heavily, both natives and non-natives, and that has been causing exactly the same problem that we are seeing in our forests as well."

Not only are the species' population growing, but their size has increased as well, she explained.

"I was sent a photo of a rat that was caught in Central Wellington and it was the size of a possum. I haven't ever seen a rat that big before, so there's certainly seems to be some correlation between a masting event and the size of rats."

Hubscher emphasised that even though there is rat problem in New Zealand urban areas, Kiwis should spare a thought for defenceless native animals in our forests which are dealing with exactly the same thing.

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"Forest and Bird are concerned we might see local extinction in forests that don't have comprehensive predator control programmes in place - and most of New Zealand doesn't."

For example, there are kokako in Auckland, in both Hunua and Waitakere, and also the predator-free Tiriti Matangi Island.

Hubscher said kokako need fewer than 5 per cent rats (per 100 traps) to breed successfully, but with the alarming number of rats around, kokako and other native animals could be in serious trouble this year.

Aerial rat toxins were used successfully in the Hunua ranges last year to protect the Kokako. Photo / Forest & Bird
Aerial rat toxins were used successfully in the Hunua ranges last year to protect the Kokako. Photo / Forest & Bird

Forest & Bird have tried to prepare for this year's mast, but their trappings could not keep up with the increasing numbers of rats, Hubscher explained.

"Forest & Bird have been warning about this year's mast since last year - we knew it was going to happen and we have been preparing our trapping groups for the huge explosion of rat numbers."

"But what we know is that trapping works really well in between mast years, but we just physically can not clear traps fast enough to deal with the numbers that we are seeing in the forests.

"We need to look at other methods of predator control as well, and that includes toxins and aerial 1080 as well.

"Aerial rat toxins were used successfully in the Hunua ranges last year to protect the kokako, but the Forest & Bird trapping group in Waitakere, where no toxins are used, are worried they may be overwhelmed by rats and stoats this year."

Hubscher revealed that the Department of Conservation is doing the best they can with the resources they have got, but they need more resources to manage the problem.

"We need more Government investment in controlling these problems and we need future proofing as well because mast years will become more common because of climate change."

Hubscher mentioned the best way to deal with rats and mice in urban areas is to set up a trap in their own backyard, making sure it's safe and secure, so that it doesn't cause problems for any other animals and for people.

She also recommended joining a local community trapping group and/or a Forest & Bird branch as they will have lots of resources, information and support on how to trap rats properly.

How to protect your home from rats

The Ministry of Health provides tips people can follow to control these pests, and keep their family safe.

Baits and traps

• Poison is an effective way to control rodents and can be purchased from supermarkets and hardware stores. Always read and follow the instructions.

• Rat and mouse traps can also be used and are available from supermarkets and hardware stores too.

Removing food sources

• Store rubbish in secure metal or thick plastic containers with lids.

• Do not leave plastic rubbish bags outside overnight, if possible.

• Keep the inside and outside of your home clear of food scraps and rubbish.

• Do not leave extra pet food out.

Reducing their habitat

• Remove weeds, overgrown grass, rubbish and other materials that could provide hiding places for rodents.

• Secure any gaps or cracks in your home to stop rodents getting in.

(Source: Ministry of Health)