OI,.. speaking of ferals, the lady next door has been feeding them for years. This past season I hand raised two litters (which were adopted out through Kitty Haven in Seattle) and trapped and tamed three other litters. In addition I helped out at six spay/neuter clinics in which we did between 35-50 cats in one day (and often dogs on top of it in smaller numbers). I live in an area without animal control, and without the low-cost spay/neuter services I don't know what I would do.
I actually trapped and tamed the biggest nastiest tom, who is now our shop cat and is neutered/has shots. It took me six months, but he's a dandy now.
I wish people would contain and control their animals and, dear lord, SPAY AND NEUTER. Feral cat life is NOT pretty, I found a dead cat today, and I found two last week (one of which was partially eaten by coyote, hawk, or some other predator).
The darn cats ruined over 1 ton of hay my first year- it was SOAKED in cat urine. I had kittens born ON TOP OF my saddle, kittens born in a bucket, and kittens under a rose bush. It was INSANE. I felt like my life was dominated by cats- and I didn't even own one although I do possess a rather lovely allergy to them.
Keeping my buff americans near the barn, and allowing them to nest there, does keep the cats out- MOSTLY- but poses other problems (goose poop ALL over the concrete and in the stalls). This is minor compared to the overwhelming amount of cat urine and dung from before, which is all the more reason to praise my beloved geese.
I don't think anything short of territorial geese could keep the cats out.