So in the post your pet thread, there were a number of anecdotes of cats bringing in dead animals and the like, and I made the following assertion: To rephrase with the benefit of hindsight: I assume that cat owners who let their cats roam freely are accepting the good chance that it will kill other animals (possibly vermin, possibly birds, possibly bird-vermin) and that there is a higher chance of the cat being killed or otherwise harmed by everything that's out there in urban or rural areas. The following counterpoints were made: This I addressed in thread as linked (also including a link to WWF advice on how to provide a safe outlet for the hunting/stalking instinct), but it does mark the introduction of "not as many are killed as by feral cats" into the argument. Again, my point is not that owned cats running free are the key factor in birds/wildlife dying, but that if you let them do so, you are accepting the possibility that they will kill things and/or be killed/harmed themselves as a routine chance you take on a daily basis. This becomes far more certain when you have a known killer on your hands. Some cat owners then shared their own explanations for why they choose to control their cats and keep them indoors. Alligator, Ingmar shared their reasons and the latter shared an encounter with a cat owner who regarded it as cruelty to keep cats indoors. To which @Llhowon asserted the following: It is indeed impossible to say what is true for all cats in all ownership situations. It is entirely reasonable to think about your cat's desires the same way that dog owners adapt to the exercise/play needs of their pets by modifying their daily routines accordingly. However, I just want to underline that the triggering argument that cats are likely to engage in killing (especially if you've already seen them kill) or be harmed/killed themselves is not at issue in this statement. The question of how you modify your pet's behavior in accordance with your ethical sense, concern for the environment, and concern for their well-being is a tricky one, but ultimately it is on the pet owner when they decide the answer to that is free roaming cats. That's really all I want to be clear about: that it's not an accident or a quirk when killing or dying happens. From there, we have a number of interesting directions: Alligator with her belief that cats can be raised to be indoor, Lhowon with more cat psychology, Sjofn with turning outdoor into indoor, Adam B with the adaptation process of Oboe. That's where it gets interesting, as MrsWidget details her struggle with the ethics of cat ownership, and NyimaR states: Which is, in fact, the position I presume cat owners have when they make that choice. Finally, Meserach states the following with reference to scientifically grounded arguments: I would just say it's worth clicking on the link which does agree that cats kill a lot of things, has no stance on the risk to the cats themselves for obvious reasons, and is making a different sort of argument designed to refute alarmism about the degree to which cats harm the environment in Britain (it does seem like other places with other situations could still be a lot more vulnerable) relative to habitat destruction or pollution. That is "don't wage war on domestic cats if you care about birds", which I think is pretty reasonable. So, that's where it stands, and I think it's good to have a place where we can argue opinions and data on ethical/environmental/etc decisions about pet ownership or continue the existing conversation without angsting up the nice thread further.