Thought I'd chime in with my 2 cents worth. When we moved in to our current place about 3 years ago, we discovered that the next door neighbor was feeding a large (40+) colony of feral cats. It has taken a couple of years of biting my tongue, being polite and doing a lot of the work, but we finally got the cats gone.
We trapped the ones that we could, but eventually you run out of dumb ones that will actually trip the trap. When that happened, I turned to the wisdom of BYC for help and got a GREAT tip... acepromazine. Since it sounds like you have horses, you probably already have some. I put about 10cc in a can of cat food, pulled up a chair so I could keep track of the critters and waited. I may have dosed a little light because it took about an hour for them to slow down enough to be catchable. But in the end we got 'em!
I still have a good relationship with the neighbors, probably better than I would have had without the cats, since we spent a lot of evenings devising traps worthy of Wiley Coyote.
Yes, there were times I would have like to call animal control and just let them deal with it but sure didn't want to start a feud about my critters.
Oh, if you can get the girls, the toms will eventually go away. And praying for a hungry owl doesn't hurt either!