Cat owners are using new technology to impose strict curfews and prevent the pets hunting at night.
Debate around protecting native birds and other wildlife from cats has polarised public opinion and economist and philanthropist Gareth Morgan has urged people not to replace their family cats as they die.
However, microchipping technology can be used to keep cats from leaving the house during set times, particularly when cats are likely to prey on wildlife.
The cat doors function by communicating with microchips already implanted in cats.
Auckland-based Cat Door Company said it installed about 40 microchipped cat flaps last month and the curfew mode is increasingly popular.
Microchipped doors cost $270 to $370, plus installation.
Until recently, smart flaps were mainly to keep neighbouring cats away, but even for this purpose, microchipping goes further now.
Aucklander Kim Gudsell said the device kept nuisance cats away and gave moggy Romeo peace of mind.
"I'm not having half the neighbourhood's cats in the house, taking all the cat food and doing who knows what else in the house. Also then, my cat can relax in its own home."
Cat Door Company chief executive Grant Jackson said most customers chose an overnight curfew.
"You can set it so at six o'clock at night it locks. Once they come in, they can't go back out."
SureFlap New Zealand manager Raewyn Carter said microchip-enabled flaps could be installed in walls and glass doors. A door could be set to recognise up to 32 different pets.
The SPCA advises the rice grain-sized microchips be inserted under the skin, giving each pet a unique code and allowing the SPCA to find owners of animals found wandering.
The flap was big enough for small dogs such as shih tzus, chihuahuas and sausage dogs. SureFlap also hoped to release a microchip-controlled feeding bowl in around September.
Forest and Bird advised people to keep cats indoors at night, to stop them hunting wildlife. The Department of Conservation had similar advice. Cats are crepuscular - most active at dawn and dusk - and keeping them indoors at twilight lowered the risk of their contracting disease from strays or getting injured.