Cosmo – The cat debate and whether cats kill wild life is not something that NCAT will get involved in.
The issue is whether it is reasonable for the OC to prohibit something based on some subjectively unproven future event.
In my opinion it is not reasonable for the OC to ban a cat based on your reasoning, regardless of how individuals within the OC personally feel about cats.
Your OC is entitled to place conditions on the approval to keep a cat. If the conditions are breached then the approval can be withdrawn by the OC.
Conditions may be that the cat is to remain indoors within the apartment at all times when the occupants are absent from the apartment, and may only be permitted within the confines of the outdoor courtyard under the strict supervision of an adult occupant.