Welllll folks, we have the same kind of feral cat problem. Talked to the vet about it and he made some calls around and told me we would have to find a different soulution than "trap, spay, and release". That procedure is very expensive and expecially dangerous for the personell involved. We have been hoping for a 'virulent bug' to come along the past two winters (something wiped out all our farm cats about 15 years ago), but no luck there. The feral cats we have just moved in on their own several years ago, maybe three of them, and then just started multiplying. Right now there is not a mouse or rat within 1/2 mile of the place. I will be looking for a 'sharpshooter' soon. Either that or trap and drown in the cow tank.
Then the deer situation has gotten way out of hand. During the depression, when hubby was a kid, they hardly ever saw any deer, because the farmers ate them...didn't have deer or wood ticks either back then so no Rockey Mountian Spotted Fever and/or Lymes Disease. We find fresh deer dropings on our lawn every morning. Last year this time we had "Deer Damage" tags that the DNR had us issue for antlerless only. 12 deer were shot between May - October, and they are still running in herds and up to 30 at a time can be counted in one alfalfa field or another at night.
The 'critters' are taking over !!!