Invasive Rats in New Zealand Could Destroy the Ecosystem and Native Wildlife

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​The invasive rats in New Zealand have been a major issue for the past decade. The population has risen sharply and is now at an all-time high. The invasive rodents cause harm to New Zealand's native species, as well as damage infrastructure and property. Rats are one of the most destructive invasive species, as they eat both living and dead animals, crops, and poison baits intended to kill them. In response, New Zealand is gearing up to eliminate invasive predators by 2050 - including possums, stoats, and other invasive predators. These animals will be killed or trapped until their populations decline enough that there are no longer any significant effects on native wildlife from these pests!
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Invasion of Rats in New Zealand
The first rats to arrive in New Zealand were introduced by Maori settlers more than 700 years ago. By the time Europeans arrived in New Zealand, there were already several invasive rat species present. Around 1855, ship rats spread across New Zealand's North Island and eventually reached the South Island sometime after 1870. The population of rodents has risen sharply, and they now pose a significant threat. Many species, such as the famous kiwi and the massive kakapo parrot, have lost the ability to fly. They were gentle and settled, and as a result, they were easy pickings for rats, dogs, cats, stoats, weasels, and possums that arrived later on. Over 26 million baby birds and eggs are eaten by these animals every year.

What Are Rodents?           
Rodents are mammals with four front teeth that grow continuously throughout their lives. They have a single pair of chisel-shaped incisors, perfect for gnawing through hard materials like wood and plant matter. A long, thin dental groove on the outer side of each upper incisor delivers blood to an elongated tooth socket where the incisor attaches to the skull. This groove also allows rodents' teeth to self-sharpen as they wear down from gnawing, which is why invasive rats in New Zealand are so destructive!

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Photo by Joshua J. Cotten on Unsplash

​Rodents in New Zealand...
In New Zealand, there are four distinct species of invasive rodents.

House Mouse
The house mouse (Mus musculus) is the most common invasive rodent in New Zealand. It is very small and slender, averaging around 6-11cm in length (including the tail). It has reddish-brown fur with a greyish belly.

Ship Rat 
The ship rat (Rattus rattus) is New Zealand's largest invasive rodent, with an average length of 32-46 cm. It has coarse greyish-brown fur and a long tail that typically ends in a white tip - though this can sometimes be black or even yellow! Unlike the other invasive rodents, the ship rat is nocturnal - active at night.

Norway Rat 
The Norway rat (Rattus norvegicus) is New Zealand's second-largest invasive rodent, averaging around 28cm in length. It has coarse fur that varies from light tan to dark reddish-brown on its back with a greyish belly.

Kiore
The kiore (Rattus exulans) is the smallest invasive rat in New Zealand, averaging around 23cm. It has reddish-brown fur with a grey belly and typically lacks the black coloring on its close relative, Ship rat. 

Rodents are fearless creatures that are highly adaptable to both urban and rural environments, making it easy for them to invade New Zealand. Invasive rodents have been nomadic species since the time of the dinosaurs! These animals can travel over large areas in search of food and can even swim across ocean water when their populations become too high.

There is no way to fully get rid of invasive rodents, even with invasive rat control. They are intelligent creatures that will adapt to their environment in order to find food and shelter. However, they can be managed through invasive rat management strategies like trapping or poisoning - provided you act fast! Because rats can reproduce rapidly.

New Zealand Mice Infestation Threatening Lives 
Over the last decade, rat infestations have become a serious problem in New Zealand. They are cat-size and brazen, invasive rodents that are invading New Zealand homes. These invaders have been known to invade houses, garages and even warehouses searching for food - often entering through unsealed vents or holes around pipes.

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​According to CNN, "rat infestation plagues New Zealand town. In the artsy west Auckland suburb of Titirangi, rats have infested businesses and homes. Within 20 minutes, the reporter witnessed 30 to 40 rats.

The rodents now pose a serious threat to people's houses and their health and cause damage to infrastructure. New Zealand mice infestation is increasing, which now has the government scrambling for invasive rat control solutions.

Boom Period for Invasion of Rats in New Zealand
New Zealand's rats had enjoyed a boom period during the lockdown, as the lockdown allowed them to run amok in cities. During this time, invasive rat infestation had significantly increased.

Malcolm, director of Māori-oriented biosecurity business Puna Consultants, says," "For the first time, my whānau [family] has gotten to see me doing pest control. I told my family that we must do this to protect the birds.” Many of these threatened birds are treasures. The local government is aware of the importance of preserving Nara's natural treasures with special cultural meaning. “The taonga species are included in our whakapapa: “I believe we have a responsibility to help them because they helped protect our tupuna [ancestors].”

The country's most vulnerable animals are being threatened as the number of rats, mice, and stoats grow. That is why the country has decided to work towards invasive rat eradication by 2050 to protect its citizens and native wildlife!

New Zealand Rat Eradication Plan
The country is getting ready to eliminate rats by 2050. The nation's people wish to eliminate all invasive mammal predators to protect their citizens and native wildlife!

New Zealand invasive rodent eradication is difficult because of rodents' high adaptability. The country has prioritized eradicating invasive predators by 2050 to protect New Zealand's threatened species, such as the Kiwi bird.

Many of the country's conservationists and citizens have rallied behind Predator-Free 2050, an extraordinarily ambitious plan to save New Zealand's birds by eliminating invasive predators.

Use of Technology to Eradicate Rats
The use of gene-editing technology may assist New Zealand's invasive rat eradication effort. The invasive rodent control scientists are using gene technology for invasive rat eradication. 

Gene-drive systems have been proposed to fight invasive species that threaten ecosystems and biodiversity, but the safety risks associated with such strategies remain unclear. In particular, it has not been determined whether populations can develop resistance mechanisms against CRISPR gene drives.

Invasive rat control scientists like to use invasive rodent eradication technology that has been tested and proven maximally safe for the environment and its inhabitants. This is why they prefer using gene editing solutions to invasive rodents! 
Use of Traps
On the other hand, Predator-Free 2050 is also working on ways to use tried-and-true technology. The most frequently used traps are snap traps, but they are not always efficient. Rats and stoats can be killed by self-resetting traps that fire a gas-powered piston to the head or traps that spray 100 stoats with poison before needing to be reset. 

Other companies are creating sensors that will alert trappers when their snares have caught an animal, allowing them to avoid spending time checking everyone.

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​Use of Poison
Many islands have been rid of invasive predators by using poison. However, the use of 1080 pesticides has come under a bit of fire from conservationists and animal rights activists as it is very toxic to New Zealand's wildlife, such as kiwi birds and kea parrots.

Using pesticides more effectively requires better ways of detecting pests, such as footpad sensors that may track a rodent's footsteps or cameras with automatic analysis by artificial intelligence. Another group is likewise working on developing unique poisons by analyzing the genome of possums to discover compounds that would only harm the 

Russell, a young ecologist New Zealander who was born and grew up in the country, says, "Even if we don't reach the finish line, the fact that we ran most of it will be quite amazing.”

Wrapping Up
The invasive rat eradication effort in New Zealand is one of the most ambitious conservation efforts ever undertaken. The country has prioritized getting rid of invasive predators by 2050, and many are helping them achieve their goal!

The objective of the government is to eliminate pests by the year 2050. The economic drain from animal pests in New Zealand is significant. The government spends roughly $NZ70 million each year on animal pest control programs, and invasive predators cost the country an estimated $NZ3.3 billion in lost productivity per year.

Russell's team had to develop cutting-edge methods that are still in use. Russell is hopeful that the country will ultimately be freed of all invasive predators. Still, at the very least, he believes that New Zealanders have been taught a valuable lesson from this experience.

Predator-Free 2050 could set a precedent for other countries to follow suit. This could be the very first domino that starts an epidemic of "island-eradication!"
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The elimination of all invasive predators is still possible, but it will lie in our hands whether we succeed or not.

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Author

Nida Riaz is a freelance blogger based in Pakistan. She started writing about her passion for the environment when the world came to a stop in early 2020.

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