The trouble with feral cats

Environmental protection agencies are encouraging the introduction of bylaws and microchipping to help control feral cats in the region.

Tasman District councillors voted to include feral cats in its regional pest management plan last month and are awaiting a report on what the future of a cat management bylaw would look like.

Department of Conversation (DOC) senior ranger biodiversity for Rotoiti/Nelson Lakes, Melissa Griffin, labels feral cats as one of the main causes of the decline in local kea.

“Kea populations have declined quite dramatically in the eastern part of the South Island,” she says.

Unlike rats and stoats which commonly target eggs and chicks, cats can also prey upon adult kea which have the added disadvantage of primarily feeding on the ground, making them vulnerable to predation by feral cats.

“They will use the whole environment, a tom cat can move kilometres, so it’s a huge environment they can be found in so there’s no real safe place… for our fauna.”

As part of DOC’s trapping of feral cats in the Nelson Lakes area, it has a census of cats in the St Arnaud village which contains a photo of peoples’ pets and a brief description of the animal. Cats are also encouraged to be collared, which further helps DOC identify pets.

“Without all of these things, it would make it very difficult to trap cats near the village,” Melissa says. “You can’t really tell the difference; cats get feral inside a cage when they feel like there’s a strange person there.”

Gillian Bishop, chair of the Tasman Environmental Trust, says feral cats are also a problem around the Waimea Inlet – a focal point for many restoration and biodiversity enhancement projects.

They prey upon native estuary margin birds, like the banded rail, marsh crake, and fernbird in addition to lizards and even insects like wētā.

The Trust traps cats around their project areas and releases the ones that are microchipped.

While families that live nearby have been receptive to the Trust’s efforts to get their pet cats microchipped, Gillian says that a cat management bylaw that mandates microchipping and desexing would be beneficial.

“Every little step you take to protect the wildlife from the predators… increases the likelihood [of environmental recovery],” she says. “Microchipping and registration are readily accepted by the community, and desexing would be a really good move as well to reduce the population.”

SPCA Nelson centre manager Julie Jane illustrates microchipping makes a massive difference to the effectiveness of their operation.

“In the last seven months, SPCA Nelson centre has had 241 strays in, and we’ve only managed to reunite 42. That’s 17 per cent, and that’s because they’re microchipped,” she says. “That makes a big difference in being able to reunite the animal, but also accountability if the animal’s sick.”

SPCA scientific officer Christine Sumner adds that large stray cat populations, which can be countered through desexing, didn't only impact native wildlife through predation.

"Cats can also negatively impact vulnerable wildlife through the spread of disease such as toxoplasmosis, which can be the cause of death for Hector’s and Māui dolphins."

She also mentions that stray cats could contribute to feral cat populations in rural areas.

"Improved cat management that is both humane and effective will require diverse approaches such as promoting responsible cat ownership at a national level, in addition to local engagement to ensure cat management is relevant and properly monitored," Christine adds.

Scott Burnett, Forest and Bird’s regional conservation manager for the Top of the South, says that ultimately, he’d like to see a National Cat Act to give councils guidance on how to manage cats.

But in the absence of that, he thinks introducing bylaws would help change peoples’ attitude on cat ownership.

“We’re on a bit of a journey from having cats as pets and letting them roam freely to realising that we need to be more responsible cat owners,” he says. “That’s not a magic bullet in itself, but… making microchipping mandatory makes it that much easier for conservation groups.”

Nelson City Council is expected to discuss adding feral cats to the regional pest management plan early in July.

Tasman District Council staff are working on a report to be brought before elected members in the future for consideration of a cat management bylaw.

Tasman previously decided not to enact a cat management bylaw in 2021.