Presents an overview of scientific evidence on the effectiveness of TNR programs, including field studies, literature reviews and mathematical modelling.

It is difficult to conceive of cats as constituting a problem. They are, after all, wonderful companions for an estimated 23% of Australian households. But for every one domestic cat there are an estimated seven feral cats. Feral cats pose risks to native wildlife through predation and disease transmission. Many of the native animals feral cats kill are threatened or endangered species.

Cat advocates claim the only ethically acceptable way to reduce feral cat numbers is Trap-Neuter-Return (TNR). Unlike lethal alternatives, such as euthanasia, TNR involves trapping, sterilising and releasing feral cats back into the environment. TNR is strongly supported in the United States by cat advocates and support for it in Australia appears to be increasing. However, TNR is not supported by wildlife advocates, who claim it is ineffective and poses unacceptable risks to wildlife.

Legally, the status of TNR programs is uncertain. Releasing cats back into the environment as part of a TNR program may constitute an offence of abandonment or unlawful liberation. The Animal Welfare (Population Control Programs) Bill 2014 is a Private Member’s Bill introduced in the Legislative Assembly on 11 September 2014 by Mr Alex Greenwich. Its primary objective is the removal of the legal uncertainty surrounding TNR programs. Although the Bill provides some operational safeguards for TNR programs, they are of an indirect and discretionary nature. Overall, the Bill is based on the premise that TNR programs are effective and have minimal negative consequences. As the Second Reading Speech to the Animal Welfare (Population Control Programs) Bill 2014 states:

TNR is likely to decrease population sizes and therefore have a beneficial effect on the ecosystem. But even if it is incorrect to say that TNR is effective in decreasing population sizes, it certainly cannot increase them and so the ecosystem would be no worse off than it otherwise would have been.

This paper presents an overview of scientific evidence on the effectiveness of TNR programs, including field studies, literature reviews and mathematical modelling. For the moment it is enough to say that the evidence is somewhat mixed and far from conclusive.