Well, I would suggest going to some of the areas you've seen them roost before and wait until its almost dark. Some people say listen for them to fly up..... personally I feel if you hear them fly up your too close, might spook them when you leave. Anyway, try an owl hoot. It works great!! They will gobble to it immediately. Giving away thier location and thats where you head in the morning...... owl hoot also works wonders in the morning aswell when they are still in roost. Give it another "hoot" in the morning when you slip in, just to make sure he is exactly where you thought he was. Good Luck!