A key part of TNR is the "R" part- "Return". In order to effectively control the cat population, the trapped cats must be returned to their original environment after neutering. This prevents the vacuum effect depicted below by Alley Cat Allies.
One must also consider the reasons for not wanting the cats to return. Most unwanted behaviors that bother communities vanish after TNR. Some behaviors that stop after TNR include:
- Spraying (and that pungent odor)
- Multiplying-- The population will be controlled and you won't wake up to four times the cats you had last spring.