Cats will be banned in a future Hamilton subdivision, based on a court ruling designed to protect native bats that are approaching extinction.
The feline-unfriendly measures were recommended by the Environment Court for the planned 105ha Amberfield development, to be located near the western bank of the Waikato River in Peacocke.
Such a ban is believed to be the first of its kind in an urban environment, and aims to protect the nationally-critical pekapeka/long-tailed bats.
The river corridor is a long-established habitat for bats, and there are roosting populations all along the river.
The land proposed for development has until now been rural. However, in the coming years thousands of new homes are expected to be built in the area - over 800 in the development in question - which raised concerns for the bat population, which is declining by between 6 and 9 per cent a year and approaching extinction.
The ban, which would also apply to rats and mustelids, was first mooted by independent commissioners after a resource consent hearing for the Amberfield development, but was appealed by developer Weston Lea Ltd to the Environment Court.
The Department of Conservation also challenged the consent conditions, but argued they did not go far enough to protect bats. The Riverlea Environment Society Incorporate and Forest & Bird registered as interested parties to the case.
Cats are among the main predators of New Zealand's bats, the country's only native mammals, along with possums, rats, and stoats.
Evidence supplied to the Environment Court showed just one cat had killed more than 100 short-tailed bats in a week.
Judge Jeff Smith ruled the logic supporting a cat ban in the area was "almost irresistible".
The bats are a nationally-critical species. There was no doubt cats predated bats, which roosted in trees, and introducing another 840 residents to the area would "significantly increase the density of cats".
The area in question was one of the "most sensitive areas" for bats in the development, and while it would simple to remove such a ban if necessary, it would be "virtually impossible" to apply one retrospectively.
A cat ban also "fits well within the ethos of this area as an ecological development area which is also dog friendly", Smith said.
Forest & Bird senior lawyer William Jennings said while the ruling was a "big win for the bats", it would also help protect many other native species predated by cats, particularly birds.
He didn't believe it was the first "cat-free zone", as other bans had been in place to protect species including kiwi in Northland, but it was the first time a court had imposed one on a new subdivision.
While the court had not decided on how the ban should be enforced, Jennings said it could take the form of covenants placed on properties that did not allow for residents to have cats.
The decision could serve as a precedent for areas around the country where cats predated on critical wildlife populations, Jennings said.
"I think wherever we have threatened species, and some form of development is proposed, this could be used."
DoC Hauraki Waikato Taranaki acting regional director Tinaka Mearns said they were "very encouraged" by the decision.
"We believe the judgment gives a positive way forward and we look forward to working with the parties on the finalisation of the consent conditions."
In his ruling, Smith said the consent was a "positive way forward" for the bats, but urged Hamilton City Council to pursue a catchment-wide approach, particularly given other developments planned.
Further issues included avoiding disturbance on the river corridor from light and noise, providing suitable areas for roosting on the river and through its adjacent gullies, and improving the habitat quality.
"The long-tail bat is at a critical stage in Hamilton.
"Hamilton needs urgent work to maintain and improve bat habitat largely based around the Waikato River and its gullies.
"The ongoing encroachment of residential activities around the edges of the river could be the final blow for the bats."
Smith instructed Weston Lea to prepare a draft set of conditions that followed the terms of the court's interim decision, and circulate it to the interested parties for further discussion within 20 days.
Weston Lea general manager Steve Bond said they were still working through the decision, but were looking forward to working with all parties to finalise the consent conditions.
"Weston Lea remains committed to protecting long-tailed bats, which are a primary ecological management consideration for Amberfield."
Hamilton City Council city growth general manager Jen Baird said the interim decision supported their "vision to create an attractive and sustainable community in Peacocke" along with work to protect the natural environment, particularly native long-tailed bats.
The council did not currently have a policy around the control of these cats, rats and mustelids, as pets, and staff were working through how this could be managed.
Long-tailed bats are smaller than the short-tailed bat, chestnut brown in colour, have small ears and weigh 8-11g.
They are believed to produce only one offspring each year.
They can fly at 60km/h and have a large home range of about 100sq k.