As much as I love cats, I don't see them as highly trainable. They are better at training us, than we are at training them.

I would consider their highest value as what they do naturally: rodent control.

But the best mousers are allowed to stay with their mothers until they are three or four months old, so momcat can teach them to hunt properly.

The way that rats and mice multiply, I don't see how even the best rat cats could ever completely eliminate the population. Sites on the web say that one pair of rats and their offspring (50-70 per year) can produce a million rats in 18 months. I don't know if that is true, but I'm sure that they can produce a LOT.

And mice are probably pretty good at their multiplication tables, too. "The average lifespan of a mouse is 12 months. The young are born about 19 days after breeding and mature rapidly. A single female may have as many as eight litters per year, averaging five to six young each. By three months the young are independent and capable of reproduction."

And even if they did eliminate every mouse and rat, more would move in from the surrounding area. They're opportunistic, just like coyotes, raccoons, opossums, wolves, dogs and... cats.

But think of your food supply in a hardcore, long-term survival situation WITHOUT cats.