Catmandoo,
Now that you mention it, our cats are into full time rodent control since they are now let out of the house each morning. I've seen at least one mouse or mole gifted by the walkway each day. We keep the cats in at night because, wev'e lost several over the last two years to coyotes.
One of the cats likes to walk with me when I go to the pond to feed the fish. I'll bet the snakes can sence the cats are around.
Chickens are also a good bet, I've seen what they can do to a mouse that found its way into the chicken yard, an it was not pretty.
Cats, chickens, or moth balls should cure your snake problem, nypondguy.
