Yesterday - i saw i frog near a rock - i at first thought it was stuck - it was making a sound almost like calling or crying. I moved the rock and found a small snake with the frog's leg totally in it's mouth - they the went into the water and up the other side of the rocks. The snake was tan and with black markings. I would like to discourage the snakes, but keep frogs, -- would a fake bird or anything like that work? It was really amazing i must say.

So, I guess you didn't get to rescue the frog? I pulled a frog out of the jaws of a dragonfly larvae once years ago. I'm not that great at identifying snakes. Try looking at http://www.enature.com
Based on what you've said, I'm afraid it might be a water snake. Unlike garter snakes, rat snakes, etc., water snakes stick around ponds longer and are good at eating fish and frogs. Snakes don't care about fake birds. To deter them, reduce the rocks and cover near the pond. I don't want to do that since I want those things and you probably do too. If you get a snake who sticks around, you may want to have someone relocate it.