I read the heartbreaking article about large numbers of unwanted cats and dogs inundating animal rescue shelters. Although not about Rotorua specifically I am assuming the situation is much the same here.
It said warming temperatures (global warming) is causing year-round breeding.
Unless such organisations as the SPCA are prepared to get political and make law changes I can't see anything changing anytime soon.
Nationwide microchipping should be compulsory and owners held to account.
New Zealand has a large feral cat problem but it is out of sight and out of mind.
Humane euthanasia is preferable to neuter and release.