What is (TNR) Trap-Neuter-Return?
TNR or Trap Neuter Return is widely accepted as the most successful method for reducing free roaming and feral cat populations in a given area. Feral cats can quickly populate an area creating a number of hazards for local community residents and wildlife alike. The cats compete for resources and generally have a poor quality of life due to fighting over food and shelter, and overpopulation.
TNR uses live harmless traps to capture the cats without harming them or causing them additional stress. The cats are then transported to a veterinary clinic where they are treated for medical issues, desexed and ear tipped. Some TNR programs also vaccinate cats while they are in the care of a veterinary medical professional to keep rates of feline infectious diseases to a minimum. Once they are awake and healthy, the cats are released back into their colony area.
The ear tip allows volunteers in the area to see immediately if a cat has been sterilized already to avoid bringing the same cat twice to a clinic. The cat can be released and the trap can be reset to hopefully catch a cat that has not been through the program.
Trap neuter return is more successful than trap and kill because simply removing the colony as a whole will allow new feral cats to move into the space, creating the same set of problems you were facing before. TNR allows cats to stay in their home colony area without reproducing and creating more kittens, thus keeping the population down.