Right before it's completely dark, slip in to an area where you believe the birds sleep for the night. Call like an owl, or use a coyote howler, or a box call. If the birds respond, you should have an idea where they are, and start there the next morning. If no response, try another location, but once it gets later into the night, the less chance you have of getting an answer.
Another option would be to try & be in the woods and watch when they fly-up, and set up within 100 yards of where they roost. But I've only been able to do this a few times, most of the time the birds roost in different trees in the spots I usually hunt, it's a hit or miss proposition at best.