Hi Dan. The squirrel dogs use sight, hearing, but mostly scent to find the squirrels. I normally wait until late morning to squirrel hunt giving the squirrels time to leave a scent on the ground and also time to get away from the den trees. The wildlife dept. in Oklahoma did a video of us hunting, if you are interested. You tube outdoor Oklahoma squirrel hunting archery will find it. It is a little long, twenty minutes or so.