24 July 2019

What type of rat has moved in with you?

You might be surprised to learn that there are actually three species of rat here in New Zealand, each unique in their own way. Understanding their differences can go a long way toward ridding your home of them for good.
What type of rat has moved in with you?

If you have a rat problem, chances are you want them gone. Quick. And if you’re like most people, you’ve probably assumed that all rats are the same, right?

You might be surprised to learn that there are actually three species of rat here in New Zealand, each unique in their own way. Understanding their differences can go a long way toward ridding your home of them for good.

New Zealand’s Three Types of Rat

If you’ve spotted a rat or two roaming your home you’re in the majority. 2019 has seen rat populations in New Zealand skyrocket - the result of a mega mast and rising global temperatures. DOCs science advisor Dr Graeme Elliott found that “In some places we’re looking at a tenfold increase in the rodent population,” with cities in particular seeing a boom in rat numbers. Increased numbers mean increased sightings as rats move into our living spaces. But what type of rats are you seeing? In New Zealand we have:

  • Ship rats

  • Norway rats, and

  • Kiore, also known as Pacific rats.

Where do they prefer to nest and what do they prefer to eat? With this information you’ll be best placed to outsmart your local rats.

1. Ship rats

Also known as black rats or roof rats, these pests are some of the most likely to plague your home, particularly if you live in or near our central cities. They range from 12 to 17cm long and weigh up to 300gms. They have scraggly fur that can be black or medium to light brown and one of their hallmarks is an underside that is lighter than the rest of their body.

They prefer to live in trees (they’re mainly arboreal in nature) but in urban areas they’ll come indoors to nest. Being great climbers, walls or roof cavities are some of their favourite spots if nearby trees don’t fit the bill, often gaining access by climbing trees onto your roof before finding a way inside.

In urban environments, low lying rubbish and compost provide an abundance of food for Ship rats, while in more remote areas with native bush, seeds, berries and small animals - like birds are their staple diet. On farms they often feed on crops, feed and, if you’re really unlucky, machinery upholstery and wiring.

Tip: Consider what available food could be attracting them to your home and take steps to make sure they can’t get into it.

2. Norway rats

Norway rats, also known as brown rats, are much larger than Ship rats, often totalling up to 50cm, including the tail. They can weigh up to 500g - that’s twice as much as a black rat , and they dwarf the common house mouse. Their coarse fur is usually brown or dark grey, and they have a lighter underside.

DOC find that Norway rats are more typically associated with human activity and found in urban areas. They have also been found on more than 60 offshore islands, which means they’re very adaptable to different climates, and they’re as at home in the heat of Northland as they are in the damp bush of Auckland’s Titirangi and the cold of the deep South. Norway rats build their nests in underground burrows or at ground level to stay warm, so if you see holes in the soil around foundations or through your garden, you could have a resident family of Norway rats. It’s also worth mentioning that they’re great swimmers, often called ‘water rats’, so you might spot them near lakes and rivers or in backyard pools. 

Similar to the Ship rat, Norway rats flourish in urban environments because we feed them, and although they develop food preferences over time, they’ll consume what is most easily and readily available. That includes food scraps, compost, vegetables in the garden on your property as well as your neighbours. As Norway rats have a home range of up to 900m, anything within that range will feed and draw them in.

Tip: When considering what food sources are available for rats, look beyond your property and think about whether your neighbours need to be part of your rat control solution. 

3. Kiore

The kiore, or Pacific rat, are uncommon. They’re only found in New Zealand around Southland, Southern Westland, Fiordland, Stewart Island and a few other small islands. So if you’re living in one of our main cities, odds are you don’t have a kiore problem. Kiore are smaller than both the Ship rat and Norway rat, have brown fur which is darker along the spine, with grey and white on the belly.

Kiore are as adaptable as the Ship and Norway rat, living in various bush types including beech forests, kānuka forests, coastal scrublands and tussock grasslands as high as 1300 metres. They feed on seeds, fruits, leaves, insects, lizards, and the eggs and chicks of some of our most loved native birds. Unlike the Ship rat and Norway rat who nest in trees, homes and underground, the kiore prefers to shelter amongst rocks and tree stumps. Unlike other rat types, kiore are relatively solitary.

Getting rid of your rats

So, you know you have rats. You even know what type, where they prefer to nest and what they may be eating. How can you trap them? Trap location is the first step. Finding where your rats are most comfortable feeding helps know where to put your trap.

To help you find that magic spot where your rats are feeding, we’ve developed trap location cards which come with our Smart Trap Kits. These are small chew cards filled with paste that you place around your property. Once they’ve been nibbled on, you’ve found where to put your trap.

Traditional snap traps require a lot of time and effort to maintain as they need regular emptying, resetting and re-baiting. These types of traps also don’t guarantee a quick death for the pest. Our Smart Trap solves each of these problems!. The Smart Trap automatically resets itself after every strike, killing 24 rats (or stoats, or mice) before you need to reset it. Our trap uses a long-life paste that automatically dispenses over six months and attracts any type of rat.

With the Goodnature Smart Trap you get constant control of rats in your area with minimal effort. It also comes with a Smart Cap which tracks how many times your trap fires, so you’ll know how many rats you’ve killed.. See it in action here.

In our next blog we discuss rodent detection in more detail along with how to manage competing food sources on your property. The two go hand in hand.