Our neighborhood has lots of cats. Lots. So far I know about 20. They all run loose and don't belong to anyone,they just live under sheds and in the woods. I've heard there is some sort of cat birth control that can be put in food - is this true? Are there any spay/neuter services for them if I were to trap and transport? They are welcome to come back and live here and I'll handle any after surgery care,and I'll also pay for pain meds. No idea how I'd administer,though,since they are only semi-tame.
I'm not sure where you live but Tri-County did have a catch and release grant that paid for ferals to get fixed. I think if you want a 100 percent sure method of controlling the population, that is the way to go.
I have posted about this in the past when my mother-in-law's slut of a cat kept getting knocked up. She had so many litters of kittens I have seriously lost count, I think 7 or 8. My husband and I ended up getting involved and after we snatched her last litter of kittens, he (my husband) showed a strong temper with his mother and insisted food and water stop. He got her trapped and fixed. Kudos to him for doing what he did because even the Humane Society wasn't able to catch her after months of trying and sadly way too many nice friendly kittens get put down every year for lack of homes so a nasty one doesn't stand one iota of a chance.
With the slut, as soon as she woke up from surgery and seemed to have her wits back, she was released. She lives on the farm and stays close by. It would certainly ease your mind to not have to deal with after surgery meds going that route.
Call the Humaine Society and see if the grant is still something you can work with....