Honestly, I don't think there is anything you can do. I know there are plants and things that will deter mammals, but I don't think there is anything made that can deter reptiles. I can ask a reptile forum if you'd like.

Since it's getting warmer and there is such a large abundance it's probably why it's noticible. Once they realize there are predators in your yard (aka the dogs), they'll likely move on on their own.