Once again you are seeing the rersult of habitat destruction. In Minnesota the native rattlers are down drastically in numbers and range; today only a maximum of a couple dozen sightings are reported per year which is down from a couple hundred just a couple decades ago. The other snakes are nearly as bad. I only find a half dozen or so large snakes per year rather than the dozens I found as a kid. Large snakes up here are hognose, bull, rat, and the occasional king snake along with the afore mentioned rattlers. Also missing are racers, skinks, and, in the amphibians, salamanders and, to a lesser extent, toads. Even garter snakes are not as common nor as large as a few years back. I have a "snake mound" constructed and the numbers using it have dropped in the past several years. The difference is there are more houses pooping up in the area and the loss of habitat must be having an effect.