I think regular vampires probably controlled the feral population for hundreds of years. Only in the last 3 years after the volcano, have they let them run free.

They may even have not let them live at all so they would remain hidden. Like putting down rabid dogs if dogs could be born rabid. I thought in the show they said you would risk going Feral if you didn't feed soon after turning. What was the reasoning they gave for becoming Feral?

@Bobby vs Satan said:

They may even have not let them live at all so they would remain hidden. Like putting down rabid dogs if dogs could be born rabid. I thought in the show they said you would risk going Feral if you didn't feed soon after turning. What was the reasoning they gave for becoming Feral?

They become feral from consuming animal blood instead of human. Not feeding just makes them hungry. I assume if they go too long without blood they'll starve. But if they start feeding on animals, after a while they get brain damage (or something like that). Once that happens they'll stay feral even if they take down a human. The damage is irreversible. I assume this is why there were no feral vampires before The Rising. They kept a low profile and their numbers were small. Once they started running around biting lots of people there wasn't enough human blood for everybody. They just let the feral ones run wild. I don't think the intelligent vampires care one way or the other what happens to them.