Predator-free plea: 'We need more than just a rallying cry'

14 July 2017

One year on, support for Predator Free 2050 – the bold government-backed project to rid NZ of possums, rats and stoats by 2050 – is gathering pace, but scientists are warning it's an impossible goal.

As well as numerous rural projects around the country, Wellington, Picton and Auckland have launched predator-free strategies, with Dunedin and Nelson about to follow suit.

Yet ecologists say that even with public backing, the government's initial $28 million investment is not enough because pulling off the goal will require significant scientific advances.

Andrea Byrom is the director of New Zealand's Biological Heritage, which is trying to find new scientific solutions to deal with pests.

While she likes the aspirational vision, we need to make a distinction between eradication and suppression, she says.

Eradication is getting pests to zero, which we do really well on islands and are respected around the world for.

With the current tools and technology, the eradication of predators on mainland New Zealand is not possible, although incremental improvement in existing technologist like ZIP is promising.

Community support and involvement are an essential part of the movement, she says.

"Part of the reason why there's been such a groundswell of interest around this is exactly because the government decided to back Predator-Free 2050. We can argue all we like about the amount of funding that's been put out there for that – we know $28 million is not enough – but the point is we need to tackle this issue on a number of fronts."

Victoria University's Dr Wayne Linklater, who has come up with a new lure for trapping pests, isn't convinced the war will be ever be won.

Introduced predator control will always be part of conservation in New Zealand, he says.

"We need to do it better, we need to do it more humanely, we need to do it with less poisons."

The government's Predator-Free 2050 policy is based on a science-fiction rather than science, he says.

Some of the tools it proposes, such as genetic manipulation, carry biological uncertainties and risks that the public hasn't heard about, he says.

"I think we're being conned.

"As an ecologist, I would be much more inclined to engage with the realities, and the realities are that goal can't be done."

We need to develop new tools and learn to implement them better, he says.

And while the community is doing awesome work, a strategic national vision is needed, he says.

"I really would like to see conservationists stand up and say, 'Stop giving us the unreal and start giving us the real. Start giving us freshwater standards that work. Stop trading conservation lands for poorer quality lands."

Kaipara couple Gill and Kevin Adshead are bringing back kiwi to their Mataia farm and working on community pest control projects like the Forest Bridge Trust.

Kevin applauds the government for putting a line in sand and says we need to keep the momentum up.

"Eradication may never be possible, but certainly suppression is."

"We strongly believe kiwis should be able to live in this environment without being especially fenced in."

It may be unachievable to rid New Zealand of predators by 2050, but it's this 'line in the sand' that is galvanising community groups, says Jill.

"When we were smokers there was a fantastic programme in schools and our kids came home and said to us 'Mum and Dad, why do you smoke?' We want kids in shools to go home and say to their parents 'Why arent you trapping pests, Mum and Dad?' I think if that happened all over New Zealand – our population is five million – then we'd get five million pests if everybody set a trap."

If you are interested in what's being done to combat predators in your community, the PFNZ Trust has mapped over 1,000 community groups and individuals throughout the country involved in predator control.

Innovative lures to improve rat control

A Victoria University of Wellington research project has been awarded more than $360,000 to develop more effective lures to manage rats, one of New Zealand's, and the world's, most damaging mammal pests.

12 July 2017

The Department of Conservation has invested in research to improve predator control through its Tools to Market fund, that are designed to support New Zealand’s Predator Free 2050 goal to eradicate possums, rats and stoats in the coming decades.

One of its funded projects is being led by Victoria researcher Michael Jackson.

“Traditional lures for rats and other pest species like possums are foods—things like peanut butter, chocolate and cinnamon. The problem with these foods is they’re perishable. They are only attractive for a few days, meaning more cost and time to keep monitoring devices and traps replenished,” explains Michael.

“We have identified five chemical compounds found in a variety of foods that are attractive to rats, and will develop these into long-life lure products.”

Michael, who recently submitted his PhD thesis, will work with Associate Professor Wayne Linklater and Dr Rob Keyzers from Victoria’s Centre for Biodiversity and Restoration Ecology to transform their research into viable products. Turning the five compounds into a low-cost, easy-to-use product is the projects main focus.

“There are many options for how these compounds could be dispensed, such as aerosol sprays, emulsions or aromatised plastic blocks. We will carry out trials in different devices, and in both urban and forest environments, to help us determine the best option,” says Michael.

“The ultimate aim for our project is to develop a product that ensures traps will be consistently attractive over a prolonged time period without the need for human intervention. The lures will also be easy to handle and store, cost-effective, and able to be manufactured on a large scale.”

Michael says wild rodents are a significant pest issue internationally, and a new tool to lure rats offers a substantial export opportunity for New Zealand.

“Rats are a problem not just for conservation but also for agriculture, food storage and processing, and human and animal health. In Asia, for example, the estimated rice lost every year to rodents could feed about 200 million people. Rats also transmit diseases like leptospirosis and salmonella.

“We’re delighted to receive funding from the Department of Conservation, and excited about the impact our new lures could have.”

Targeting tiny terrors in the Pacific

Ants in New Zealand might be annoying, but in the Pacific, invasive ant species are tiny terrors that are destroying food crops, blinding pets and livestock, and forcing people off their land.


Pacific Biosecurity, a non-profit organisation operating out of Victoria University of Wellington’s School of Biological Sciences and supported by Viclink, Victoria University’s commercialisation office, is halfway through a five-year project funded by the New Zealand Aid Programme to improve capacity to deal with invasive ants.

The researchers involved say the results so far are positive.

“We’ve been collaborating with regional and in-country partners over the last two years to control yellow crazy ants on Atafu, Tokelau and eradicate them in Kiritimati, Kiribati,” says Dr Monica Gruber, Pacific Biosecurity’s programme manager.

“We are delighted to report that we have significantly reduced ant numbers so that they are no longer causing problems.”

The acid-spraying yellow crazy ants are capable of mass attacking and killing animals over 500 times their size—including crabs, and nesting seabirds and their chicks—posing a significant threat to local ecosystems.

“Despite the huge impact of these pests, communities weren’t able to do anything to manage the ant populations because they couldn’t afford pesticides or other methods of ant control,” says Dr Gruber.

The New Zealand Aid Programme funding enabled Pacific Biosecurity to help with control of the ants, and develop the Pacific Invasive Ant Toolkit (PIAT), a website and a collection of resources designed to help biosecurity staff, consultants, village councils and homeowners to prevent and control invasive ants in the Pacific.

Currently, the toolkit is being rolled out to in-country and regional agency partners through a series of workshops. The workshops cover how to prevent ant problems, including community awareness-raising and biosecurity improvements, and how to manage problems when they occur, including determining the best practice method of treatment and the safe and effective use of pesticides.

“The results we’ve experienced, and the feedback we’ve been getting, show that our work is having a positive impact,” says Dr Gruber. “Our in-country partners appreciate the resources we’ve created to enable them to more easily identify invasive ants, carry out risk assessments, and undertake programmes to control invasive ants.”

Pacific Biosecurity will also be using some of the New Zealand Aid Programme funding to deal with the yellow crazy any problem in Tuvalu.

Additionally, later in the year, the team will work with colleagues from the Biosecurity and Trade Support Team at the Pacific Community (SPC) to implement an integrated pest management programme for mealybugs in Fakaofo, Tokelau.

Dr Gruber says the team is grateful for support from Viclink.

“It was Viclink that advised us to set up our group as a distinct entity, and then helped us to apply for funding. There’s always a risk involved in any new initiative, but they’ve shown complete faith in us all along, and given us the freedom to be creative about designing and implementing solutions.”

For more information visit the Pacific Biosecurity website, or contact Dr Monica Gruber on 04-463 5026 or monica.gruber@vuw.ac.nz

First evidence of rhinoceros’ ability to correct gender imbalance

Research led by Victoria University of Wellington has demonstrated the ability of rhinoceros to modify the sex of their offspring to avoid the dominance of one gender and limit severe competition for breeding.


The study, led by Associate Professor Wayne Linklater from Victoria’s School of Biological Sciences, provides the first experimental evidence in the wild that unbalanced population sex ratios can result in a compensatory response by parents to ‘correct’ the imbalance.

“This is called a homeostatic sex allocation (HSA) response—a biological theory first proposed in 1930,” explains Associate Professor Linklater.

“Almost all population models assume birth sex ratio is fixed. Our evidence indicates that this may not be the case.”

The study, published today in Nature Ecology & Evolution, was co-authored by Dr Peter Law from Nelson Mandela Metropolitan University in South Africa, Pierre du Preez from Namibia’s Ministry of Environment and Tourism, and former Victoria University postdoctoral researcher Dr Jay Gedir.

The research team examined 24 years of rhinoceros data, gathered during the course of 45 reintroductions of the animals across southern Africa.

Sex-bias is especially important in rhinoceros populations due to their critically low numbers, says Associate Professor Linklater.

“But because of the evidence of HSA, we need not be so concerned about that misbalance, because parents appear able to ‘correct’ it when they breed.

“HSA has an especially strong effect when the gender imbalance is very large. In fact, the further it is from an even-sex ratio, the stronger the response is by parents.”

Associate Professor Linklater says that those populations where HSA is possible will be more resilient. “Their small populations will have improved establishment and greater viability. Such species will populate habitats faster, and be less susceptible to random demographic processes and genetic drift.”

Explaining the allocation of resources by parents among male and female offspring is a leading issue in evolutionary biology, says Associate Professor Linklater.

“Extreme sex ratios commonly occur, so the incidence of HSA will significantly impact our understanding of a range of ecological processes including invasion biology and conservation management.”

The study was completed with funding from the United States Fish and Wildlife Service’s Rhinoceros and Tiger Conservation Fund.

Associate Professor Linklater now plans to do further research into how an HSA response works in Australian brushtail possums. This includes how competition to breed triggers the effect and at what point in the reproductive process the mother is able to control the sex of her offspring.

“Possums are ideal subjects for such a study because their offspring are born into the marsupial pouch at an extraordinarily young age—very early in development—and so can be studied in great detail,” he says. “Possums are also invasive mammals in New Zealand. Understanding their reproductive processes can provide new ways of managing population numbers.”