Instructions
Call your local American Society for the Prevention of Cruelty to Animals and inform them of the feral cats that you wish to have spayed or neutered. The ASPCA will send a member or volunteer out to set up traps to catch the feral cats. Once they have caught them they will bring them in and have them spayed or neutered at no cost to you. The ASPCA is a "No Kill" shelter; if the feral cats have a suitable temperament, they will offer them out for adoption. The ASPCA also endorses the "Trap-Neuter- Return" or "TNR" policy. The TRN humanely traps the feral cats, brings them into local animal shelters to be spayed or neutered and then returns them where they found them so that they may live out their lives.
Go to the Feral Cat Project's website and read their step-by-step instructions on their "TNR" policy. They offer specific instructions on how to trap a feral cat, where you may bring it to be spayed or neutered for free and how to return it back into the wild.
Go to the Humane Society of the United States' website and click on your state's abbreviation. Locate a feral cat organization and inform them of the feral cats you wish to have spayed or neutered. Depending on the organization, they may ask you to trap the cats and bring the cats to them or they may send out volunteers to trap them and bring them in for you. They will have the cats spayed or neutered and will release them back into the wild if they are unsuitable for adoption.
How to Spay & Neuter Feral Cats
Feral cats can live in your neighborhood or deep in the woods. A feral cat differs from a stray cat as feral cats are born in the wild and do not know the lifestyle of a "house" cat, while a stray cat was usually someone's pet before getting lost or being released. Feral cats may have adjusted to living in the wild and might not be suitable to be someone's pet. However, it may be necessary to have them spayed or neutered so that they will not keep having litters of feral kittens.