You have
- cars
- cruel teens
- insane adults
- coyotes and shit
None of those are good for the cats! Keep them at home!
And Stuff You Should Know pod ep on the topic says feral cats lead horrible lives (75% mortality 6 months after birth) - so decreasing their numbers via TNR is amazing. Apparenly high intensity TNR (hitting >70% pop) reduces feral cat deaths 30 times! 30! That's a lot of kittens who don't die horribly.