There is a difference between a stray, which may have been someones pet and was dumped or lost, and has had human contact. If you find a stray, you should take it to a vet or shelter to check it for a microchip that identifies the owner. Sometimes strays, if left without homes long enough will become part of feral colonies, but many times will still be friendly to humans.
Don't be fooled into thinking that if you successfully catch and remove all the feral cats that you have solved the problem. That only creates another issue called the Vacuum Effect. Essentially what happens is like there is a for rent sign up where the cats that you removed were. Ferals need shelter and a food/water source in order to survive. If they have found this then when you remove them, other ferals will find this same space and more cats will take up residence, and the whole situation repeats itself.
The best solution is TNR (Trap, Neuter, Release). Humanely trapping them, having them neutered and releasing them back to where you found them. The average lifespan of an outdoor cat is considerably shorter than your protected house cat. Eventually the colony of cats will become smaller. When a cat is neutered it is usually eartipped, a process when the vet cuts a piece of the ear off. It's a universal symbol that the cat has been spayed, and is part of a colony.
There is additional information available from www.alleycat.org or you can contact the Animal Care Sanctuary locally here in East Smithfield. www.animalcaresanctuary.org. I have also left literature at Rockwells Feed Store, God's Grace Pet Grooming, and at the Canton Sentinel for more information.
This month, in October the Animal Care Sanctuary is hosting Catoberfest. All Spays and Neuters are $35. You can make an appointment by calling 570-596-2000.
Note: This TNR process also works for barn cats....farmers you can control your cat population too. For those with house cats who are unneutered, keep in mind that having your cats spayed/neutered will be better for their health and avoid such problems as cancers or other issues.