Research labs take them for free. You need some feral cats to take care of the feral mice and rats unless you want to deal with feral snakes.
I had a feral cat lay her feral kitties in my bushes. I couldn’t find anyone who would take them for free. Did have a neighbor suggest I take them to a vet and have them checked out.
Then the momma tried to take my leg off.
Here in Florida we already have plenty of feral snakes. Neighbor found a coral snake in his yard. The feral hawks keep them down though.