Comment: Aloha IBrakeForBirds!

According to HHS, who does the contract killing for the City and County it costs them around $72 to catch and kill.  That may be more today.

When you catch and kill a cat you do not slow down the reproduction rate.  You increase it.  The colony will reproduce at a faster rate.  If you return neutered cats into the colony the reproduction rates decrease.  It's simple biology.