I agree with Lisa, here. It is mostly city folk who will drive to the rural areas to drop off unwanted cats, and even dogs. 
They seem to think they are being "kind" and the animals will have a life of freedom. 
This is sadly not true - kittens earn hunting skills from their mother. They do not just instantly turn feral. They freeze, starve, get hit by cars, or are grabbed up by predators. 
If they do manage to survive, they will develop diseases , especially internal and external parasites. 
Having lived here for more than 30 years, mom got a rep for taking in strays, an has had up to ten cats at one time, all needing veterinarian assistance, plus paying for the food. There is no excuse for this behaviour - there are any number of shelters who will take in babies or adults. It's just ignorance and cruelty, and they just don't get it.