I used to live in Fl Keys and we had plenty of black rat snakes, along with rattlesnakes. I think rat snakes inhabit most of the US, I have caught them here as well as FL. With the snake being young and smaller it probably is not big enough for rats yet. And unfortunately as much help as snakes are they just cannot keep up with rodent breeding. If you have one rat you have plenty more, sorry. You may need a cat if you don't have one, but they will kill the snakes too.