Wellington could once again be a haven for brown kiwi in seven years if a mayoral candidate's vision becomes reality, but it could mean bad news for cats and dogs.

Current deputy mayor Justin Lester's big idea would reduce the number of predators in the region to make it a pest-free environment.

He admits it's an "ambitious" idea, but has worked successfully with other native bird species in the region including tui and kākā.

"The bird life has been greatly assisted by Zealandia, but an extensive pest eradication scheme implemented by the city and regional council also greatly contributed. It's time to step up to the next level.

"Wellingtonians love our natural environment and are enjoying seeing native birds return to our suburbs," Mr Lester says.

If elected to take over from current Mayor Celia Wade-Brown, Mr Lester says he'd work with a number of groups including the SPCA, The Halo Project and other conservation groups to get rid of rats, stoats, possums, weasels and ferrets.

He says under the "right conditions" the kiwi could be returned to specific reserves around Wellington.

But while Forest and Bird agrees with making the city pest-free, having the flightless bird back in town would mean strict rules about cats and dogs.

"Kiwis are problematic because dogs and cats are major predators in the wild," Forest and Bird Wellington chair Colin Ryder says.

"You run into a problem because generally people keep those animals as pets and you'd probably have to keep cats inside at night and dogs on leads.

"Part of the problem, for dogs in particular, they like the smell of kiwis and kiwis are very fragile because they don't have a sternum, so a dog can pick it up in its mouth and kill it."

Mr Ryder says there have been cases outside Wellington where a single dog has killed several kiwi in one incident.

But he says having a predator-free city was "technically possible" and wouldn't be too much of a stretch from the work already done by more than 140 community conservation groups.

It would involve a major trapping operation, which would include a buffer zone.

"If they have an incursion, the area is hit very hard. There's nothing new about the approach, it's just a matter of scale."

Mr Lester says kiwi were once common in Wellington and it could happen again.

"[It's] realistic to think we can repopulate Wellington with kiwi again. Let's bring back these iconic birds back home to Wellington."

Geoff Simmons, from the Halo Project, says the idea would be a "call to arms" for people to get behind the idea of getting rid of pests.

It could turn Wellington's 'Coolest Little Capital' title into the 'Natural Capital', Mr Simmons says.

The plan also has the backing of the SPCA and the Polhill Restoration Group, which says areas like Polhill Gully and Makara Peak, targets of trapping programmes, would be "ideal" places for kiwi.

Newshub.