Wellington's leaders have officially announced plans to make the city the world's first predator-free capital - a goal researchers say is possible.
The ambitious effort has now prompted calls for Auckland to step up and follow suit.
Those behind Wellington's plan say a predator-free city would mean that birds, lizards, geckos and other native fauna could thrive in the city, bringing big environmental and economic benefits.
It first involves eradicating stoats and rats from the Miramar Peninsula, where possums were eradicated a decade ago.
A strategy would then expand the work across the nearly 300sq km of Wellington city's territorial area, with plans for a "strategically located containment control zone".
Although 90 per cent of possums have already been cleared from the area, it's estimated that around 10,000 remain.
Without any control, authorities believe possum numbers could swell to around 52,000, while rats would number in the millions.
The effort, a collaboration between Wellington City Council, Greater Wellington Regional Council and the NEXT Foundation, doesn't involve cats and dogs, but owners will be encouraged to be responsible.
Wellington City Council environment partnership leader Tim Park said the plan, which he said wouldn't require major policy changes, was "definitely do-able".
"Especially on the Miramar Peninsula 'island' - trapping and poisoning programmes over the past decade have already led to a significant decline in the numbers of rats, stoats, possums, rabbits and other pests around the city - the new initiative will go further and enable local residents to take a major role."
Mayor Celia Wade-Brown said Wellington already had a strong foundation to build from, with more than 120 volunteer restoration projects working in the network of reserves along with significant council investment.
"This next step will enable the project partners to work with local communities to build the momentum that will be critical in sustaining the project over the long term."
The plan has already funded the role of a "community champion", with pest-killing local man Kelvin Hastie recruited for the job.
After Hastie's work helped eliminate 184 rats and 27 stoats and weasels in Crofton Downs - leaving none left when checked again a year later - the NEXT Foundation backed him to carry on the work in Wilton, Ngaio, Khandallah, Wadestown, Highbury, Northland and Plimmerton.
"Kelvin is like New Zealand's urban predator hunter," said the foundation's chief executive, Bill Kermode.
"He has shown in Crofton Downs how his unique charm, individual thinking, and enthusiasm can mobilise communities into action to become predator free."
The collaboration, which would also be seeking Government investment, has also been backed by Conservation Minister Maggie Barry.
"Returning kiwi and our other iconic bird species to our capital may once have been a fantasy but we know we have the tools, know-how and commitment to achieve it," she said.
Capital plan can be done: experts
Auckland University ecologist and pest expert Dr James Russell said the peninsula Wellington sits on, bordered by State Highway 1, was an obvious choice for attempting to remove mammalian predators, as reinvasion could be manageable.
"The challenges lie in the mixed land use across the large area and finding the combination of methods which will be acceptable to everyone."
Geoff Simmons, manager of the Morgan Foundation, which has been involved in major pest eradication missions, thought the biggest surprise of the announcement was that it aimed toward total eradication, rather than just suppression.
"It is a much bigger call, much more difficult and expensive - the advantage is once it is done it is done, you don't have to keep trapping.
"Once you eradicate in an area the question is how you defend it."
Zero Invasive Predators were working on non-fence technology to do this but in Miramar the airport acted as a natural barrier.
"Beyond that there is a motorway acting as a barrier for phase two - Wellington-wide - but even then you have the risk of reinvasion with the port," Simmons said.
But Russell said more and more predator free projects at scales never before considered possible in New Zealand were now being seen.
Along with the Government's major "Battle for our Birds" pest-busting effort, the country also had large efforts like Project Maunga and Reconnecting Northland to use as stepping stones toward its goal of becoming predator-free by 2050.
Landcare Research's managing invasives portfolio leader Dan Tompkins saw the initiative as addressing an important key gap in the drive toward the national goal.
"While large-scale efforts have traditionally been placed on managing mammal pests in the conservation estate and our rural landscapes, a different approach is needed in towns and cities.
"And this is an essential piece of the jigsaw.
"Without also managing predators in these areas, any efforts to make our conservation estate and rural landscape predator free would be quickly undone."
With a different range of issues and concerns to be met when controlling pests in these areas, the community engagement approach was critical to success, he said.
"Particularly exciting is that this initiative will motivate similar efforts in other urban areas around the country."
Environmental Defence Society policy analyst Dr Marie Brown, author of the new book Vanishing Nature: Facing New Zealand's Biodiversity Crisis, agreed.
"The concept of a predator free Wellington is something the public can grab on to, and there is room for everyone to play their part.
"Much of our remaining biodiversity is near city centres in New Zealand, making urban restoration an important part of conservation generally."
Navigating the complex social dimensions of the goal - and properly integrating cats into the game plan in due course - would be no mean feat, she said.
"But a strong conservation presence already positions Wellington well to lead the way."
Could Auckland be next?
Russell saw Auckland as an important part of the predator-free New Zealand plan, given it could act as a narrow and easily defendable bottleneck which could protect the entirety of Northland.
"In its own backyard Auckland could well focus its effort on a Predator Free Waitakeres, to help protect its water sources, and reconnect the Waitakeres to the Hauraki Gulf islands."
Auckland Council biosecurity manager Brett Butland said the challenge and opportunity in the country's biggest city was to extend control efforts beyond predators to include all pest species that impact on native ecosystems and species.
"There are places in the region where browsing animals such as rabbits and weed species are as much of, if not more than, a threat to our native ecosystems," Butland said.
Auckland was investing in the trial of new technology, including telemetry-based trap monitoring, self-resetting traps and biological control agents.
"To achieve a pest-free Auckland will require involvement and commitment from agencies and communities and on-going effort to prevent the arrival of new pests through our borders.
Major operations already under way around the city included Kaipatiki Local Board's Pest Free Kaipatiki project and targeted landscape-scale efforts in wildlife corridors like the North-West Wildlink and on Hauraki Gulf islands.
"Auckland Council supports the national commitment for New Zealand to be predator-free by 2050 and welcomes the Wellington councils' initiative," Butland said.
"In Auckland, we want to step that challenge up a notch - towards a pest-free Auckland."
Stu Barr, director of pest solutions company Goodnature, which is now involved in large-scale operations with the Department of Conservation, said he believed that from the Waitakere Ranges to the city centre, Auckland had the potential to be pest-free.
"The city has created a number of pest-free havens in the Hauraki Gulf, showing that Aucklanders have the desire and capability to eradicate pests," he said.
Auckland's geography was such that it was well suited to creating onshore sanctuaries, he said.
"What's so exciting, is that it's achievable and using the tools we have, we can get started right now."