TNR is an abbreviation known as Trap, Neuter and Release. It is a program dedicated to reduce overpopulation of feral (wild) cats. Some are semi tame or tame enough to try finding a home for while most are released back with volunteers providing them food, shelter and water for the rest of their lives. For a male cat, it only requires 24 hours to stay indoor to recover after surgery and it takes a female cat several days.
TNR is strictly for feral cats, but the clinic also welcomes stray cats if needed. The overpopulation of feral cats has gotten out of control. Sadly, feral cats were originated from domestic cats where irresponsible owners do not spay/neuter their cat(s) and let them roam freely outside. Unneutered male cats are the worst as they can impregnate several female cats outside. Nevertheless, both sexes need to be spayed and neutered. It is the hands of many humans that caused the suffering of cats, be it they starve, freeze, get disease, are neglected, tortured and/or be killed.
For one cat that you do a TNR, you are saving about 12 thousands offsprings in 7 years and multiply that with several cats you help do a TNR. You'll be making a world of difference in the lives of these cats. There are volunteers involved in TNR and there's always need for more volunteers. The goal is to see less and less feral cats. It is more cost-effective and humane than having them euthanized.
If you are interested to help or get involved in your community, go to this alleycat website I am involved in this in my area and I've met these volunteers. They're caring and wonderful people. I have dropped off a feral cats I trapped to be fixed (spayed or neutered). It is inspiring to witness many volunteers with feral kittens/cats in their trapper(s) or carrier(s) to be fixed. They have about 100 or so lined up to be fixed. Since my dogs are not cat-friendly, this is the least I can do for these cats and will house them in a closed door room on a temporary basis.