WLS Success-through Powerful Positive Attitudes
Yvonne... Do you have SOCKS ???
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they sponsor events where the cost is reduced for spay & neutering and also shots. I'm not sure if this is a national org- but they try to local feral cat communities, trap and fix. Then release them back-
It's not a perfect answer but it's much better than overloaded SPCA answer of putting them down.
*Correction: Actually it's SAVE OUR CATS- KITTENS & STRAYS