For those of you that aren't familiar with the term "TNR," it's an acronym that stands for "trap, neuter, return." Some use "TTNVR" or other forms, but I prefer the simpler version. (TTNVR represents "trap, test, neuter, vaccinate, return") Obviously, "neuter" signifies both male and female sterilization. I believe the "R" stood for "release" at first, but there was some concern that the cats would simply be released anywhere - it has since been changed to "return." The cats need to be returned to their home environment to be set free. Individual vets make the decision to test, vaccinate, and treat other minor problems such as fleas, earmites, and abcesses.
So why is TNR important? First, mass extermination, which has been in effect for decades, is clearly not having much of a positive impact on the overpopulation of stray and feral felines. We've been killing these cats for years upon years and there are as much of a "problem" as when we started! Not only is it wrong ethically to kill off these animals, but it's just not working! Why are we slaughtering all these animals when it's not having any sort of impact? Because we are rooted in tradition. It's what we've always done. Trap the cats and kill them. But you know what? This leads to what is called "the vacuum effect." Though the cats are removed, the food source remains. More cats will be able to survive by taking advantage of the bounty and will move right back in. So extermination does not solve the solution.
TNR, however, addresses the issue of overpopulation by stopping the reproductive cycle. The cats are returned to their home environment to live out their lives. Not only does this prevent more cats from being born, but it succeeds in keeping other cats out. How? Because though cats are social creatures in having their own colonies and best buddies, they generally discourage newcomers from arriving and using up their precious resources. Eventually, the colony will dwindle.
Another important aspect of TNR is that most programs vaccinate against distemper and rabies and will treat minor issues such as fleas and earmites. How is this helpful? Well, simply put, TNR allows the cats to become healthier. They are able to keep weight on easier; disease is controlled by the reduction of fighting, wandering, and mating; vaccinations prevent certain maladies; and they are relieved from the irritations of fleas and other buggers for a while. Also, the practice of TNR strongly promotes the idea of caregivers for the returned cats. The caregiver ideally keeps track of all the cats (including keeping an eye out for those who may become sick), and provides food, water, and shelter. All of these will obviously promote the health and well-being of the cats. Trapping and killing does NOTHING to benefit the remaining cats. *edit* I should also mention that the healthier cats refute the idea that all strays and ferals are sickly and should therefore be put out of their misery. Strays not accustomed to outdoor living tend to be disheveled and hungry, but those who know how to survive are actually quite healthy, especially when they are provided with the resources that TNR and managing colonies offers. Those not used to free living are also then being taken care of and will thrive accordingly.
Lastly, TNR helps to reduce common complaints that are encountered when dealing with stray and feral cats. Too many babies? Check. Mating calls and behaviour? Check. Fighting? Wandering? Check. Scrounging for food and shelter in undesirable places? Check. By practicing TNR and managing colonies, we eliminate and drastically reduce these "nuisance" behaviours. We become better neighbors to our feline community - and don't even have to kill them off.
TNR has been shown to be the only humane method of feral and stray cat population control. Trapping and killing simply does not work and is not in the best interests of either human or feline society. Which would you rather have?