birth control fo feral cats

Question
I live out in the country and I have approx 7 'feral' cats that stop by looking for food. I have become attached and feeling sorry for them, so I have been feeding them.  However, I know I will have a problem soon as they multiply.  They will not let me approach them to where I can touch them.  Is there some kind of birth control I can put in their food or water to stop the rapid multiplying that I know will occur soon?  I dont want to have to starve them away before the neighbors complain about the increase in coyotes as they will surely be attracted to so many cats.

Answer
Bob,

As far as I know, there is no effective birth control that can be reliably given to feral cats.  

There are groups, e.g., Alley Cat Allies, See:

https://www.alleycat.org/NetCommunity/SSLPage.aspx?pid=196&tab=1

which specialize in Trapping, Testing, Neutering/Spaying, Vaccinating, Releasing feral cats.  Feral cats who are neutered or spayed seem to keep whole cats out of their territory.

Their web site is full of helpful tips in getting started.

Best regards... Norm.